Legislative Acorns and Judicial Oaks

Guest Blogger

For the Balkinization symposium on Diego Zambrano, How Americans Enforce the Law (Stanford University Press, 2026).

Nick Bagley and David Schleicher

Why do Americans love private rights of action? Because we really, really love them, as Diego Zambrano shows in his compelling new book, How Americans Enforce the Law. Today, more than 10,000 statutory private rights of action allow Americans to sue over things as serious as wage theft and as trivial as pet leases. They have an ancient pedigree, stretching back well before the nation’s founding. And they are at the core of basically every twentieth-century legal regime, ranging from securities law to consumer protection to environmental law. 

It’s not just that our love is so intense. It’s that the object of our love is so weird. No other country—not even other countries with a common-law inheritance—relies as heavily as we do on private litigation to enforce statutes.  (Will McAvoy can add a fourth category of things the U.S. leads the world in!)  

There’s so much to like about the book. One choice example is Zambrano’s takedown of a leading explanation for why we have so many private rights of action: Sean Farhang’s The Litigation State. As Farhang tells it, legislatures adopt private rights of action when they don’t trust the executive branch to enforce the law. Tapping plaintiffs’ lawyers to do the enforcement work, the story goes, allows the party that controls the legislature to bypass executive machinery that is, or may become, controlled by the other party. 

Farhang’s  explanation may have held water for Congress in the 1960s and 1970s. But is it true for Congress today? Of even greater consequence, is it true for state legislatures, which are responsible for the huge majority of private rights of action in the United States? 

Zambrano ran the numbers, and argues the answer is no. Legislatures pass private rights of action during divided government and undivided government. They pass them when they’re controlled by Republicans and when they’re controlled by Democrats. 

They pass them, Zambrano argues, because private rights of action are an inherited Anglo-American legal tradition; because the fragmentation of the American state, both horizontally and vertically, puts a premium on tools that can bypass governance bottlenecks; because the plaintiffs’ bar is a potent political force; and because expansive discovery and class action rules make litigation a more potent enforcement tool here than in other countries. This “layered path dependence,” not a story about partisan jostling, offers a better explanation for why we love private rights of action. 

One keen insight that comes from Zambrano’s book is that Americans don’t distrust government so much as they distrust the bureaucratic monopoly of enforcement. After all, he says, courts are just a special type of government agency, not some kind of state-free workaround. 

But courts are special—which brings us to one blind spot in Zambrano’s account. He’s interested in understanding why legislatures create private rights of action to enforce a given legal rule. It’s natural, then, that he wants to hold the rule constant. But delegating to courts will predictably affect the content of legal rules. That’s especially true in the states, with their frequently elected judiciaries. 

Consider one example from Michigan. In 1976, Michigan adopted a consumer protection law that included a private right of action. It was one of a rash of similar laws prohibiting “unfair and deceptive practices” (UDAP) that, Zambrano tells us, were adopted around the same time in every state in the country (p. 74). 

But the story of the law’s development didn’t stop with the law’s enactment. In 1999, a Republican-controlled Michigan Supreme Court read the law so narrowly that it might as well have been wiped from the books. There things stood for a quarter-century—until this past July, when the Michigan Supreme Court, now firmly in Democratic hands, overruled that decision. 

And so an initially strong UDAP law became a weak UDAP law, only to spring back into a strong UDAP law again. It would be odd to center the Michigan legislature in telling this story. Yes, it created the initial cause of action. But the shape that the cause of action took—the work that it did in the world—has largely been dictated by judges who, it turned out, had a lot of latitude to adjust the law to suit their policy preferences and the felt needs of the time. 

This story isn’t unusual. The National Environmental Policy Act famously includes no cause of action. That didn’t stop the courts from deciding, contrary to Congress’s intent, that it was the judiciary’s duty to enforce the law “to the fullest extent possible.” Likewise, courts have been instrumental in shaping the Securities and Exchange Act, including by inferring the very cause of action that Zambrano (correctly) says is instrumental to the functioning of securities law. In 1975, the Supreme Court called the 10b-5 lawsuit “a judicial oak which has grown from little more than a legislative acorn.” Five decades later, the Court would use exactly the same metaphor to describe NEPA. 

Early in his book, Zambrano says that he’s focused on “statutory private enforcement” (p. 30), not the common law. But the presence of all these judicial oaks raises the question whether our common-law inheritance may play a greater role in the story than Zambrano allows. For better or worse, judges in the United States have been pioneers not only in enforcing the law, but in making it. They are often closer to lawmaking partners than legislative agents. (Indeed, many state statutory rights of action are codifications or modifications of common law claims.) And we Americans seem to like that—or at least our judges and trial lawyers do. 

What should we make of that? Zambrano is alive to the ways that private enforcement privileges repeat players with the resources and the wherewithal to sue to protect their rights. He’s likewise alert to how hyperlitigation from self-interested parties can run counter to the public interest. His chapter on why private rights of action under environmental laws, particularly California’s Environmental Quality Act, makes this clear. But he doesn’t tell us much about the virtues or vices of empowering judges to make the law. 

Asking that question would open some interesting lines of inquiry. Zambrano says that private rights of action can reduce the risk that a regulatory regime might be stunted by bureaucratic capture or quiet agency defunding. But does that analysis hold with the same force once you consider that state court judges can be captured too? As Einer Elhauge has famously argued, litigation and legislation are both riddled with public choice problems. Variable lawyer quality, different litigation appetites, strategic settlements, and the internal contradictions of mass litigation give rise to similar problems as lobbying muscle and collective action problems for groups in politics. Should it worry us that trial lawyers bankroll the campaigns of Democratic judges? That business groups support their Republican opponents? Or is the diversification of avenues of influence sufficient to blunt the concern? Are these the same or different questions than we ask about the merits of judicial deference to agency interpretation of statutes? 

You might also worry about placing decision-making authority in state court judges.  Regulatory bodies can be sclerotic and underfunded. So can courts. Further, state trial courts frequently represent political settlements reached long ago, as intellectual changes do not filter down to the local political bodies that often control judicial election and appointment. In land use litigation, state trial courts have become entrenched opponents of development, representing NIMBY ideas that are now well outside of elite and bipartisan consensus. Further, the sheer number of judges and the ability of litigants to choose their fora in many instances may lead to less coherent policy answers than would a regulatory solution, for good or for ill. 

Finally, one might wonder whether there is some interaction between the use of private rights of action and weak state capacity. Would state and localities underfund agencies if they did not have as easy recourse through private rights of action to a vast private bureaucracy of litigators? 

None of this detracts from Zambrano’s account, of course. It just adds a layer of complexity to a story that was already plenty complex. 

Nicholas Bagley is a professor at the University of Michigan. You can reach him by e-mail at nbagley@umich.edu. David Schleicher is a professor at Yale University. You can reach him by e-mail at david.schleicher@yale.edu.