A federal appeals court handed down a major ruling last week packed with progressive ideas about the constitutional rights of those disabled by mental illness. But liberals didn’t cheer the decision or tout it as a landmark affirmation of liberty and minority rights. Why not? Because this case affirmed a right with which progressives have a rather complicated relationship: the right to bear arms. The case is the latest to illustrate a quandary that has arisen in Second Amendment jurisprudence in the years since the Supreme Court handed down District of Columbia v. Heller. Now that gun ownership has been enshrined as a fundamental right, should liberals defend that right for everyone equally—even if they disagree with Heller itself?

The issue has worked some progressives into knots. But I think it’s an easy call. When a case involving gun rights could expand constitutional equality more broadly, liberals should support it. There’s no sense in justifying or ignoring discrimination simply because the Second Amendment is involved.

Consider last week’s ruling, issued by the U.S. Court of Appeals for the 6th Circuit, that the government cannot permanently bar once-disabled individuals from purchasing a firearm. The plaintiff, Clifford Charles Tyler, was hospitalized three decades ago for a severe depressive episode after his wife left him. At the time, a court found that he suffered from mental illness and committed him to a mental hospital. Today, Tyler’s physician has confirmed that he is mentally healthy and has been for years. He’d like to purchase a firearm—but federal law forbids anyone “who has been adjudicated as a mental defective or who has been committed to a mental institution” from buying a gun. So Tyler sued, arguing that the law unconstitutionally abridged his Second Amendment rights.

Legally and medically speaking, depression is a disability, and progressives have fought for decades to create stronger constitutional protections for those deemed disabled by the state. Tyler’s case represented an obvious opportunity to further this cause, but liberal advocacy groups balked. The burden instead fell on disability rights advocates to push for a ruling recognizing Tyler’s ability to recover from past mental illness. When the court ruled for Tyler, it rebuked the government for attempting to “enshrine a permanent stigma on anyone who has ever been committed to a mental institution for whatever reason.” An extremely conservative judge hearing the case, Jeffrey Sutton, even penned a paean to the rights of the disabled, castigating the feds for applying a false, “stigmatizing generalization” to anyone who has ever suffered from mental health disabilities.

The 6th Circuit’s ruling wasn’t especially broad with regard to gun rights: It simply held that the government must give Tyler, and others in his position, an opportunity to prove in court that they should have their Second Amendment rights restored. (More recently institutionalized individuals, the majority noted, can still be barred from gun ownership.) For this price, the court affirmed the constitutional dignity of disabled people and broadly questioned the constitutionality of laws that interfere with disabled people’s liberty based on some prejudicial presumption. Its opinion laid the groundwork for future challenges to state discrimination against people with mental illness. Is that really not a worthy trade-off for progressives?

A case in the 7th Circuit provides an even starker example. The Second Amendment states that “A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.” But who are “the people” in this formulation? The Constitution guarantees several rights to “people” and “persons,” but the Supreme Court has never declared who, exactly, counts. Citizens? Lawful residents? Undocumented immigrants?

The 7th Circuit was forced to confront this quandary head on when considering a challenge to a federal law barring any “alien … unlawfully in the United States” from owning a “firearm or ammunition.” Mariano Meza-Rodriguez, who was unlawfully brought to America as a young child and never obtained citizenship, argued that this law violated his constitutional rights after he was charged with illegal gun possession. In response, the government insisted that undocumented immigrants are not among “the people” whose right to bear arms is protected by the Second Amendment. Three other federal appeals courts also reached that conclusion.

But the 7th Circuit bucked this trend. The court found that the Constitution’s reference to “the people” in the Second Amendment encompassed both citizens and noncitizens, authorized or unauthorized. Undocumented immigrants, the majority wrote, who are part of America’s “national community” or have “developed sufficient connection with this country” are protected by the Second Amendment. The court then explained that no one’s right to bear arms is unlimited, and found that the government still had an “important governmental objective” in denying gun ownership to Meza-Rodriguez because he had already “disrespected the law.” (Before his gun bust, Meza-Rodriguez had had “multiple brushes” with law enforcement.)

Meza-Rodriguez scrambled the usual ideological factions on firearms. At ThinkProgress, Ian Millhiser celebrated the ruling, noting that an adverse decision would’ve cast into doubt immigrants’ right to privacy, due process, and equal protection. The left-leaning American Bar Association called the opinion “a step in the right direction for noncitizen civil rights.” Meanwhile, conservative outlets that typically tout a near-unlimited right to bear arms vigorously opposed the decision, expressing dismay that a court had granted constitutional liberties to “illegal aliens.” But once again, mainstream progressive groups like the American Civil Liberties Union were silent, and the task of defending Meza-Rodriguez’s rights fell on smaller immigrant advocacy organizations. Meza-Rodriguez was one of the most important immigrants’ rights cases of the decade so far, and many of the most powerful usual allies for immigrants were missing in action.

Given this track record, it’s no surprise liberal litigation groups also declined to question the government’s sweeping ban on firearm possession for medical marijuana users in another recent case. Federal law prohibits any “unlawful user of … any controlled substance” (including marijuana) from owning a gun and bars gun suppliers from selling firearms to such people. The federal government currently interprets this statute to forbid even the holders of state-issued medical marijuana cards from buying a gun, no matter whether they actually use cannabis. Nevada resident S. Rowan Wilson was denied a gun under this interpretation because she held a medical marijuana card. (Oddly enough, Wilson said she did not use cannabis; she obtained the card only to make a political statement in support of decriminalization.) In a lawsuit, Wilson argued that the federal statute interfered with her Second Amendment right to possess a firearm.

Wilson’s case presented a prime opportunity for courts to apply more searching judicial scrutiny to the federal government’s sweeping claims about the dangers of marijuana. Because courts now demand that the government show some “important interest” in restricting firearm access, it might have forced the feds to explain the important interest in restricting the rights of medical marijuana users who obey state laws. There are plenty of liberal advocacy groups pushing for marijuana reform. If just a few had filed amicus briefs debunking the purported link between medical marijuana and gun violence, the court might have seriously questioned the government’s ungrounded insistence that there is “a strong link between drug use”—including medical marijuana use—and violence.

But Wilson got no support from progressive groups that have helped defend medical marijuana users in other contexts—no amicus briefs disputing the feds’ characterization of marijuana as a violence-inducing peril. (Her outmatched attorney fought the case almost entirely pro bono.) That left a noticeably exasperated court to rely on outdated and inapposite studies provided by the government. Absent contradictory data provided by Wilson, the court wrote, it had “no occasion to evaluate the reliability of the studies and surveys.” And so the court unanimously agreed that Congress came to a “reasonable conclusion” in deciding that the use of marijuana “raises the risk of irrational or unpredictable behavior,” justifying the abridgement of Second Amendment rights.

It’s easy to see why left-leaning civil liberties groups stay out of legal battles like Wilson’s, Tyler’s, and Meza-Rodriguez’s. Many still believe, as I do, that the Supreme Court was wrong to read into the Second Amendment an individual right to bear arms. But gun rights are currently ascendant in the federal judiciary—a trend that won’t likely be reversed any time soon—and firearm restrictions tend to turn rock-ribbed conservative judges into bleeding hearts. Liberal litigators should recognize that, in the right hands, the Second Amendment can be a tool for social progress. It’s time to stop fretting and use it that way.