Progressives have long been skeptical of federalism, with the role that “states’ rights” played in the resistance to the civil rights act and desegregation typically featuring prominently in their criticism. Its ugly history even led one 20th-century scholar to insist that “if one disapproves of racism, one should disapprove of federalism.” Even now, with every national institution in the hands of the GOP, progressives associate federalism with conservatism and shy away from invoking the language of federalism to change the policies they oppose.

That is a mistake. Federalism doesn’t have a political valence. These days it’s an extraordinarily powerful weapon in politics for the left and the right, and it doesn’t have to be your father’s (or grandfather’s) federalism. It can be a source of progressive resistance — against President’s Trump’s policies, for example — and, far more importantly, a source for compromise and change between the left and the right. It’s time liberals took notice.

Here are three important ways progressives can take a chapter from the conservatives’ playbook and use their control over state and local governments to influence the national agenda, shape policy results, and encourage political compromise. If Jerry Brown or Andrew Cuomo or Eric Garcetti is looking for a “to do” list for the next four years, it’s here.

Uncooperative federalism

People assume that if Congress changes a law, everything changes on a dime. They forget that Congress depends heavily on states and localities to implement federal policy. 

The federal government doesn’t have enough resources to deal with immigration, enforce its own drug laws, carry out its environmental policies, build its own infrastructure, or administer its health care system. Instead, it relies on the states to do much of this work. We call such arrangements between the states and federal government “cooperative federalism.” But we forget that they create many opportunities for what Jessica Bulman-Pozen and I have called “uncooperative federalism.” 

Progressives at the state and local level can influence policy simply by refusing to partner with the federal government. By doing so, they force issues onto the national agenda, foregrounding debates that the Republicans would rather avoid. More importantly, defeating state or local opposition costs fiscal resources and political capital the federal government would rather employ elsewhere.

The GOP-controlled federal government can’t put cops on every beat or bureaucrats at every desk; it needs state and local officials to get its agenda through. If blue states and cities refuse to implement Trump’s agenda, Republicans will sometimes be forced to compromise rather than pay a political and fiscal price. 

Deploying federalism against the Patriot Act and education reform

Sometimes states engaged in uncooperative federalism simply refuse to participate in federal programs, or they do so begrudgingly. Some states have refused to carry out the Patriot Act and federal immigration law. States didn’t just denounce the Patriot Act’s broad surveillance and detention rules as an attack on civil liberties. Blue and red states instructed their own officials not to collect or share information with the federal government unless there was a reasonable suspicion of criminal activity, or they forbade state officials to engage in activities inconsistent with the states’ constitutions.

Other states have repeatedly stymied federal education reform just by dragging their feet. States resisted the No Child Left Behind Act by manipulating testing standards and by slow-walking reforms. State recalcitrance was so great that eventually the Bush Administration threw in the towel and granted states so many waivers that the federal program was basically gutted. 

Federal dependence on states is so pronounced in criminal law that the Vanderbilt law professor Robert Mikos has suggested that states can effectively “nullify” federal marijuana law simply by withdrawing enforcement resources, as did Colorado and Washington. To be sure, Jeff Sessions, Trump’s choice for attorney general, can try to change the equation by selectively targeting a few businesses, but it will be an uphill climb.

Sometimes states take advantage of the gaps that are inevitable in any regulatory scheme to take a program in a direction Congress never anticipated. In the early 1990s, Michigan and Wisconsin, led by their Republican governors, enacted the models for “Welfare to Work” inside the very federal welfare scheme they aimed to topple. Their successes eventually won over Bill Clinton to their cause and pushed Democrats on the Hill to junk the existing system and follow their model. National welfare reform was the still-controversial result. 

States used their powers under the State Children’s Health Insurance program to provide coverage for adults. Back in 2006, Massachusetts used Medicaid funds to help enact “Romneycare,” which would become the model for Obamacare. And when states are pushed too hard, uncooperative federalism can even devolve into outright defiance (as in the case of the Patriot Act). 

Uncooperative states and towns

Uncooperative “localism” — resistance at the level of city or town — can be just as effective as uncooperative federalism. When cities refuse to assist homeland security or deportation efforts, there is relatively little the federal government can do. That’s presumably why the Trump administration is so panicked about sanctuary cities that have promised not to implement his immigration policies. (“Sanctuary cities” is not a legal term, but it typically refers to municipalities that refuse to assist with certain types of deportation efforts — for instance, instructing their police not to ask about a person’s immigration status).

The Trump administration already threatened to cut off all federal funding to such cities. While the federal government can entice states to carry out federal policy by offering financial incentives, a decision penned by Chief Justice Roberts forbids the federal government from using conditional spending to coerce state officials. (The case involved the Obama administration’s attempt to force states to expand Medicaid as part of the Affordable Care Act, lest they lose all Medicaid funding.)

Even if President Trump spends enough political capital to win this or that battle against blue cities and states, he cannot win the war. The federal government doesn’t have the resources to carry out Trump’s policies. Spending political capital and legal resources to win the marijuana dispute, for instance, takes away resources from the immigration fight or battling California on climate change. Political scientists have long talked about the power of the “street-level bureaucrat” to thwart the law the legislature enacts. But in today’s federalism, the power of the street-level bureaucrat is rarely confined to the street. 

Federal dependence on states and localities thus creates an enormous incentive for moderation and compromise. Often the only way for a national program to succeed is to have a national consensus behind it. Just ask President Obama, who had to compromise a great deal to bring Obamacare to the red states, offering individual red states waivers and incentives to convince them to join. Trump may not have to cooperate with Democrats on the Hill, but he’s going to need the support of blue states and cities if he wants to get things done. A federal program that doesn’t touch California, New York, or Illinois won’t affect a large swath of the American economy. That should create a healthy incentive for moderation going forward. 

State-level regulatory “spillovers”

Uncooperative federalism won’t work for every policy that matters to progressives. Much of the Trump agenda is deregulatory; uncooperative federalism is irrelevant when there isn’t a program to resist. But that’s where spillovers come in. When one state regulates, it often affects its neighbors. When Texas insisted that its textbooks question evolution, its market power ensured that textbooks used in blue states did the same. When Virginia made it easy to buy a gun, guns flooded into New York City despite its rigorous firearms prohibitions. When West Virginia failed to regulate pollution, toxic clouds floated over Ohio.

But spillovers, like federalism, don’t have a particular political valence. Just as there are spillovers conservatives cheer, there are spillovers progressives celebrate. Want to know who really sets emissions standards in this country? It’s not the EPA. It’s California, which sets higher emissions standards than the federal government. Because no company can afford to give up on the California market, our cars all meet the state’s high standards. 

In law, professors sometimes refer to something as a “superstatute” or a “superprecedent” to signal its importance. California is a superstate, with almost 40 million people and an economy bigger than France’s or Brazil’s. It can, in effect, enact national regulation even though it is nominally regulating for itself. Democrats seem to have won a super-majority in the California legislature. They are more than capable of sending some spillovers the way of other states. 

Here again, spillovers are ultimately a tool for encouraging compromise. In today’s heated political environment, state officials in blue and red states often lack incentives to compromise with those from the other side. But when a blue policy spills over into a red state (or vice versa), legislators can’t ignore the opposition because it is imposing its views on their unhappy constituents. They have to reach out across state (and party) lines to fix the problem. Spillovers thus force state and local officials to do what they are supposed to do: politic, find common ground, and negotiate a compromise that no one likes but everyone can live with.

Federalism as a tool for progressive change

There is one, final way in which states can be a tool for progressive values. Progressives have long thought of federalism as a tool for entrenching the worst in our politics. But it’s also a tool for changing our politics. Social movements have long used state and local policymaking as an organizing tool, a rallying cry, a testing ground for their ideas. 

The most remarkable example in recent years has been the same-sex marriage movement, which depended heavily on state and local sites as staging grounds for organizing and debate. That process may explain why those equality norms now run deep enough that the Supreme Court’s ruling on same-sex marriage in Obergefell — a decision that would surely have caused intense controversy not so long ago — was greeted with enormous enthusiasm in many quarters and opposed in precious few. 

Today we see efforts to push through other core parts of the equality project through state and local sites, including immigration reform, policing, sentencing, health insurance, and the living wage movement, just to name a few. Those pushing reform at the state and local level understand the crucial lesson from the same-sex marriage movement: If you want those policies to stick, they have to come from the bottom-up, not the top-down. And it’s useful for reformers to work through institutions rather than standing on the sideline and jeering. Social movements need pragmatic insiders, forging compromise from within, not just principled outsiders, demanding more and better from without. 

Progressive federalism isn’t a cure-all, of course. The president is more than capable of causing harm with a stroke of the executive pen. Heavily indebted states and cities may find resisting the federal government too expensive. And cities and state governments have other important business to address.

But progressives would be foolish to treat the cities and states in which they live as nothing more than enclaves sheltered from some of the national policies they don’t like. States and localities can resist policies that jeopardize the rule of law, they can create incentives for moderation and compromise when one party or another goes to the extremes, and they are the means for building shared ideals going forward. Federalism is for everyone. It’s time that liberals took notice.

Heather Gerken is the J. Skelly Wright Professor of Law, Yale Law School. Find her on Twitter at @GerkenHeather.

The Big Idea is Vox’s home for smart, often scholarly excursions into the most important issues and ideas in politics, science, and culture — typically written by outside contributors. If you have an idea for a piece, pitch us at thebigidea@vox.com.

Democrats have reason to be frustrated these days. They won the presidential popular vote and the Senate popular vote, and they were just shy of winning the House popular vote. And yet they are entirely shut out of power in Washington. The Electoral College and Senate are here to stay, needless to say, but Democrats do have an unexpected chance to make substantial gains in the House and in state legislatures post-2020 if they can convince the Supreme Court to go along. It’s a long shot, to be sure, but it’s got a better chance of succeeding than some of their other options: Jill Stein’s recount efforts or a time machine.

The unexpected ray of hope comes from a partisan gerrymandering case in Wisconsin. An eclectic group of academics and lawyers managed to pull off the all but impossible when they convinced a court to strike down Wisconsin’s state districting on constitutional grounds. The case is guaranteed a hearing by the Supreme Court, and it provides Democrats some hope of tamping down on the partisan gerrymanders that have handicapped their candidates since 2011, the last time districts were drawn.

That straight line to the Supreme Court is one reason the Wisconsin win matters so much. Most of the Court’s docket is discretionary, and the Court is not above ducking controversial questions it’s not ready to decide. But due to special procedural rules for certain voting rights cases, the Supreme Court must hear this case. Rather than “deny cert” and say nothing, as the Court does with almost all the cases it is asked to review, it must either affirm or reverse the lower court decision. (The Court can “summarily” affirm or reverse, but that’s also why the district court win matters here. The Court is highly likely to give the case a full-blown review given that plaintiffs won below.) The decision is likely to come down in the spring and, absent another miraculous win for plaintiffs in some other case, will likely be the Court’s last word on the subject before 2020. 

This is also probably Justice Kennedy’s last chance to serve as the crucial fifth vote in holding partisan gerrymanders unconstitutional. By the time another case reaches the Court, the odds are that President-Elect Donald Trump will have replaced at least one justice on the left, depriving Kennedy of his swing vote and probably foreclosing any chance of policing partisan gerrymandering during the next redistricting cycle. Today’s Court will be as friendly as any reformers will see for a good long while. 

Districting happens every 10 years, as soon as the decennial census data is released. While a few states rely on nonpartisan or bipartisan commissions to draw districts, most districts are drawn by state legislators. That means that most districts are drawn by the people who directly benefit from gerrymandering: self-interested partisan officials. That’s precisely why redistricting is referred to as a “blood sport”; it’s a chance to help your party and hurt the other side.

The GOP controlled much of redistricting during the 2010 cycle. It drew itself a set of plans that ensured, as the Princeton neuroscientist and political blogger Sam Wang points out, that Democrats would have had to win the popular vote by at least 9 percentage points to take control of the House this year. If the GOP retains this advantage as we move into the 2020 redistricting cycle, the Democrats will be at a severe disadvantage. A partisan gerrymandering rule could make all the difference. 

Why has it taken the Supreme Court so long to get involved in this issue?

Almost no one thinks it’s a good idea to have partisan legislators drawing their own districts. So you may be surprised that the Supreme Court has done nothing to halt this pernicious practice. But there isn’t just disagreement about what courts should do about the problem — justices aren’t even sure that judges should entertain partisan gerrymandering claims in the first place. 

In general the Court is deeply reluctant to move deep into what Justice Felix Frankfurter famously called “the political thicket.” Haunted by what lawyers call the “countermajoritarian difficulty,” the justices are highly sensitive about giving the impression that nine unelected people are overriding the decisions of a democratically elected legislature. 

For judges worried about invading democracy’s turf, elections are where they most fear to tread. Taking a position in almost any case means picking a political winner. Just think about the fallout from Bush v. Gore and you’ll understand why judges are reluctant to intervene.  Regardless of whether you think the Court was right to step in, many people have accused the Republican-dominated Court of picking our president. 

In addition, the Constitution is almost silent about how our democracy is supposed to work. Modern constitutions in other countries typically have a lot to say about how elections should be run. But America’s framers didn’t even anticipate that there would be political parties in the first place. As a result, they didn’t think hard about which institutions would referee political battles, let alone how to protect those institutions from partisan taint. That’s a real problem for judges looking for principles to guide them. Judges can’t decide elections cases without deciding how power should be divided, which necessarily means choosing one theory of democracy over another. 

The challenge involves finding a clear standard that can be enforced

For example, a judge can’t decide whether a districting scheme is “fair” to a political party without having an idea of what “fair” is. Should every party get a proportional share of seats? Or does democracy only require that a majority of voters can control a majority of seats? How should judges think about what constitutes political power — is it better to exercise influence in many districts or control outcomes in a few?

Given that districting always ends up disadvantaging some and advantaging others, judges also have to decide which groups deserve protection. Finally, as judges well understand, predictability is crucial for election law. It’s essential that the rules of the game be stable and fixed in advance. Deciding an election law case is thus the judicial equivalent of a high-difficulty dive, which helps to explain why the Court hasn’t intervened in a partisan gerrymandering case in three decades.

All the worries judges have about intervening in elections cases get expressed through highly technical debates over “manageable standards” and “justiciability.” Basically, the justices worry they will embarrass themselves if they try to decide partisan gerrymandering claims without an easily applied, easily defended standard. (If there’s no way for different judges to apply a rule consistently and predictably to resolve an agreed-upon problem, those disputes are not “justiciable.”)

The touchstone for manageable standards in election law is the one person, one vote test, which mandates near-perfect mathematical equality for congressional districts in a given state. The test is so simple and rigid that one justice condemned it as “sixth-grade arithmetic.” But simplicity and rigidity are features, not bugs, when it comes to manageable standards. The one person, one vote test is deeply intuitive, it’s easily applied, and it generates predictable results. Moreover, because it requires so little discretion on judges’ part, they feel comfortable applying it even in hotly contested political cases.   

You might think that the one person, one vote principle might offer a solution to partisan gerrymandering. It doesn’t. In most places, you can draw districts with equal populations and still decimate a given party simply by spreading its voters out across many districts, or concentrating them in such a way that the other party will lose most races.   

The most recent debate over the justiciability of partisan gerrymandering claims took place in 2004 in a Supreme Court case called Vieth v. Jubelirer, which challenged a gerrymander in Pennsylvania. The four conservatives insisted that the case was not justiciable for want of manageable standards. Any “solution,” they said, would just amount to substituting one politically debatable decision on how to draw lines for another. The four liberals insisted that a manageable standard existed but couldn’t agree as to what it was. And while Justice Kennedy couldn’t find a standard to his liking, he suggested he wasn’t ready to give up on the enterprise entirely.

When another partisan gerrymander claim in Texas also went by the wayside in 2006 because the Court decided the case on other grounds, lawyers decided that Justice Kennedy didn’t really mean what he said about being interested in finding a manageable standard for such cases, and they focused their energies elsewhere.

A political scientist invented a new tool to measure unfairness

Now, more than a decade after Justice Kennedy insisted that he would entertain a partisan gerrymandering claim if a manageable standard could be found, several academics and lawyers have decided to take him at his word. Eric McGhee, a political scientist who works for the Public Policy Institute of California, invented a new standard for measuring partisan gerrymanders: the efficiency gap. It tests whether a districting plan treats Republicans and Democrats similarly by assessing what share of their votes are “wasted” under a given plan. 

The concept of “wasted votes” is crucial to understanding and challenging gerrymandering. If your party is in power, you want its votes deployed efficiently, with sensible but not overwhelming majorities in as many districts as possible. You also want the other party to waste as many votes as possible — either by voting for lost-cause candidates or by widening the margins for candidates who were going to win in any case. You can spread the opposing party’s voters across many districts so they can’t garner a majority anywhere (this is called “cracking”), or you can shove lots of your opponents into a single district so they cast many more votes than necessary to win the seat (“packing”). If your side has wasted a substantially larger share of votes than the other side, the odds are that you’ve been the victim of a partisan gerrymander. 

McGhee paired up with Nick Stephanopoulos, an up-and-coming law professor at the University of Chicago, to frame and situate the standard in the case law. Through a series of fortuitous connection, their paper made its way to a group interested in challenging the GOP’s partisan gerrymander in Wisconsin, which allowed the GOP to win 60 of 99 seats in 2012 even though it won less than half of the statewide vote. The trial was run by the stalwarts at the Campaign Legal Center, including the much-revered Gerry Hebert. 

In the Wisconsin case, the district court found that an efficiency gap of 7 percent meant that a party would have almost no chance of taking control of the legislature during the 10-year districting cycle. (The actual gap in Wisconsin was 13 percent in favor of the Republicans in 2012, and 10 percent in 2014.) The redistricting, it concluded, was therefore an unconstitutionally partisan gerrymander.

Unlike other notorious gerrymanders, the Wisconsin case doesn’t involved absurdly shaped districts

The case isn’t an ideal test case, by any means. Usually gerrymanders involve “flights of cartographic fancy” — outlandishly shaped districts, like the one that gave gerrymandering its name — but Wisconsin’s districts were relatively compact. Moreover, Republicans are now in the majority in Wisconsin, so this is no longer a case where the minority is gerrymandering itself into majority control. But a better case isn’t coming along anytime soon. It may be now or never.

No one knows whether Kennedy will find the efficiency gap standard to be “manageable.” That why reformers would be wise to give him choices other than the efficiency gap standard while still taking a cue from the Wisconsin decision. 

The efficiency gap test is what political scientists call a “partisan symmetry” test because it evaluates whether the parties have been treated equally. Partisan symmetry tests are deeply intuitive. They don’t require judges to decide how many seats a party should hold, an inquiry that can make judges uncomfortable because they worry about deciding how power should be distributed. Instead, judges need only evaluate whether the parties were treated symmetrically. That is the kind of decision that judges make routinely in other areas of the law. 

But the efficiency gap isn’t the only partisan symmetry standard out there, and it would make sense to put similar standards in front of the Court. Indeed, one could imagine the Court holding that “partisan symmetry” is the right baseline for assessing gerrymanders but leaving it to the lower courts to decide which ones to use. For this reason, academics and lawyers should coordinate an effort to get the best social science in front of the Court. It’s a long shot. But, again, it may be the best shot that reformers — and Democrats — have these days.

If the Court were to find partisan gerrymanders justiciable, the immediate effects would only be felt in Wisconsin, which would have to redraw its districts. But the decision would hang like the sword of Damocles over every single districting effort that takes place after the 2020 census. The mere threat of future lawsuits would do a great deal to tamp down on partisan gerrymandering.

Politicians are delighted to gerrymander when it costs them nothing, but they aren’t willing to put their own fortunes at risk. Lawsuits are dangerous. A lawsuit not only threatens to upend existing plans but often creates the risk that courts rather than legislatures will draw the districts at the end of the day. Politicians are likely to be careful and protect their own seats rather than gerrymander aggressively to help their parties. And the aggressive gerrymanders, of course, would inevitably land in courts, which is the last place most politicians want to be. 

But right now, Wisconsin Democrats are justifiably ecstatic to be headed to the Supreme Court. Everyone who cares about reform should be ecstatic, too.

Heather K. Gerken is the J. Skelly Wright professor of Law at Yale Law School.

The Big Idea is Vox’s home for smart, often scholarly excursions into the most important issues and ideas in politics, science, and culture — typically written by outside contributors. If you have an idea for a piece, pitch us at thebigidea@vox.com.