One year after his highly improbable election, President Donald Trump woke up this morning to news that in elections across the country, candidates standing for liberty, equality, and dignity defeated Republican opponents, as American voters sent a clear message that they are not buying what the president is selling. Trump has shown disregard or outright disdain for constitutional constraints, from the First Amendment to the Emoluments Clause. But Tuesday’s election underscored that in a constitutional democracy, Trump’s ability to do damage can be—and has been—substantially checked, even when his party controls Congress and two-thirds of the state legislatures, and, with his Supreme Court appointment, has a majority on the Court. In ordinary times, Congress and the president check each other, as do the Senate and the House, the Supreme Court and the other branches, and the state and federal governments. One-party control, however, requires that we find checks and balances elsewhere—in civil society. Authoritarians know this, which is why, when they come to power, among their first targets are the press, the academy, and nonprofit advocacy groups and watchdogs.

Since Trump’s election, American civil society has indeed performed its checking function. The mainstream press, buoyed by steep rises in subscription rates, has trained the light of investigative journalism and critical opinion on the administration’s every move and false claim. The academy is a vital source of critical analysis and resistance. And nonprofit groups, new and old, formal and informal, have taken part in defending liberties from President Trump’s onslaught. From the Women’s March to the airport demonstrations to the town halls, a great many Americans have stood up in defense of what is under attack: decency, dignity, equality, and basic civil liberties. University presidents, professional organizations, national security experts, and much of the business sector attacked President Trump’s first major initiative, the “Muslim travel ban.” His efforts to repeal the Affordable Care Act have been successfully derailed, again and again, by an impressive amalgam of ordinary citizens, health professionals, nonprofit organizations, business leaders, and television celebrities like Jimmy Kimmel. Trump has failed to pass a single significant piece of legislation, notwithstanding Republican control of both houses. And his approval rating is the lowest of any president at this point in his term in the history of polling.

“We’ll see you in court,” the ACLU (for which I am the national legal director) warned Trump in the immediate aftermath of his election. We explained that we’d sue the president if he sought to implement any of his many campaign promises that contravened constitutional constraints. We have done just that, as have many other organizations, and the courts have served as an important check. Along with the National Immigration Law Center and attorneys general from Hawaii and several other states, we have sued him repeatedly over the travel ban. We challenged his administration’s effort to block the abortion of “Jane Doe,” a seventeen-year-old girl held in Texas after she crossed the border from Mexico without proper documents. We have sued him over the voter fraud commission he has created to lay the ground for the Republican Party’s continuing voter suppression efforts. We have challenged his administration’s detention of an American citizen for nearly two months as an “enemy combatant” without charges and without access to a lawyer, and the Office of Refugee Resettlement’s detention of Rosa Maria Hernandez, a ten-year-old girl with cerebral palsy who was first stopped while traveling in an ambulance to a hospital to have emergency gall bladder surgery and was then detained upon her discharge. We have also sued the president for allowing employers to deny their female employees health insurance coverage for contraception if the employer objects on religious or moral grounds. And we’ve sued him for barring transgender people from serving in the military.

Other groups and agencies have also taken to the courts. Citizens for Responsibility and Ethics in Washington, or CREW, sued Trump over violations of the Emoluments Clause stemming from his failure to separate his personal business interests from his office as president. Similar suits challenging the president’s conflicts of interest have been filed by the attorneys general of Maryland and the District of Columbia, and by nearly two hundred members of Congress. The Natural Resources Defense Council has filed many suits challenging Trump’s effort to rescind environment-friendly regulations and rules on clean water, clean air, and climate change. And numerous organizations have filed suits over voting rights, contraceptive access, and the revocation of Deferred Action for Childhood Arrivals, or DACA.

Thus far, the courts have stood up to the president. A series of courts have declared each iteration of the travel ban both unconstitutional, for impermissibly singling out Muslims for condemnation, and contrary to law, because it conflicts with an express statutory bar on denying immigrant visas on the basis of nationality. A federal court in San Francisco prohibited the administration from denying funds to states and cities that adopt immigrant-friendly “sanctuary” policies, which involve declining to enforce federal immigration law. The US Court of Appeals for the D.C. Circuit overturned the administration’s efforts to deny Jane Doe an abortion. Documents ordered disclosed in another case revealed that Trump’s voter fraud commission was indeed intended to suppress votes. A federal court in D.C. has declared much of the transgender military ban likely unconstitutional as a violation of equal protection. Just days after the ACLU sued the Trump administration for detaining ten-year-old Rosa Maria Hernandez, the government released her to her family.

It is early in this administration, and the Supreme Court has yet to weigh in on the merits of any Trump initiative. (It was slated to do so in the travel ban case, but when Trump replaced the second ban with a third version shortly before the case was scheduled for oral argument, the Court sent the matter back to the lower courts to address the new ban—where two courts have struck it down, and government appeals are pending.) But the lower courts have not been shy about ruling against the president, even in areas like immigration, federal funding, and national security where the courts generally afford presidents a wide berth. Trump, one senses, has not earned the trust that would support judicial deference. Quite the opposite, in fact, as several courts have, in effect, found that the president’s asserted national security grounds for the travel ban were a pretext, a false cover for anti-Muslim animus.

It is noteworthy that the only Republicans in Congress who have spoken out against Trump are those who are not seeking reelection: John McCain, Jeff Flake, and Bob Corker. They can candidly speak their minds. Judges, too, enjoy the freedom to act independently, by virtue of life tenure. Trump doesn’t help his cause, of course, by repeatedly showing contempt for courts and the judiciary, from Gonzalo Curiel, the East Chicago, Indiana-born judge hearing a fraud case against Trump University, whom Trump condemned for being “Mexican” and therefore not impartial, to James Robart, the George W. Bush appointee in Washington State whom Trump dismissed as a “so-called judge” after he issued the first nationwide injunction against the travel ban.

The courts, however, cannot stand up to President Trump alone, and it would be a great mistake to think they could. In the end, the most important guardian of liberty is an engaged citizenry. Popular opposition to repeal of the Affordable Care Act has repeatedly frustrated Trump’s will. Political support for the Dreamers, undocumented foreign nationals who came here as children, has greatly complicated Trump’s efforts to end DACA, the Obama program that afforded 800,000 of these young people protection from deportation. And grassroots efforts, led by groups like Indivisible, MoveOn, and the ACLU’s People Power, have inspired local engagement in defense of liberty and equality in which everyone can participate.

In a weak democracy, an authoritarian leader like Trump could do widespread and lasting damage. Such leaders often control the legislature, are immune from court oversight, and suppress civil society institutions. But our constitutional democracy was designed with leaders like Trump in mind (well, maybe not quite like Trump). And our hallowed traditions of judicial independence, civil liberties, and a robust political culture have—thus far, at least—held Trump in check to an important degree. He may be the most dangerous president in memory, but he is also the most thwarted. For those who care about civil liberties and civil rights, we need to keep it that way. The tools are available to do that—it’s up to us to use them.

This essay is part of a series reflecting on the first year since Donald Trump’s election as president.

This post has been corrected. “Jane Doe,” the pregnant girl who was held in Texas, is seventeen years old, not sixteen.