President Trump returned to a long-dormant political debate in Monday’s call with governors. He assured the governors that “I’m not a believer in flag burning,” and suggested that the states should pass a “very powerful flag-burning statute” with “strong punishment.” The president promised that the administration would “back you 100 percent,” and mused that “we have a different court” that “will accept that.”

Here’s what’s going on.

Flag burning is an old controversy

Once again, Trump was reaching back to old culture war issues to see whether they still had political life. The background is that states once had statutes prohibiting the desecration or burning of the American flag. As the U.S. Supreme Court expanded First Amendment jurisprudence over the course of the 20th century to protect a wider range of expressions of political dissent, it became doubtful that these prohibitions were constitutional.

Then a Texas judge sentenced Gregory Lee Johnson, who remains active as a member of the Revolutionary Communist Party, to a year in prison for burning a U.S. flag at a protest at the 1984 Republican National Convention in Dallas. After Johnson appealed, Texas state courts overturned the conviction on the grounds that desecrating a flag is constitutionally protected as free speech. When the state appealed to the U.S. Supreme Court, the justices split in a 5-to-4 vote in affirming the state court and striking down the Texas law.

Liberal stalwart William J. Brennan Jr. wrote the opinion for the court, declaring that public flag burning was the type of symbolic political speech that was protected by the federal Constitution. Brennan had written many of the court’s First Amendment opinions since the days of the Warren court in the 1950s, so his position was no surprise. Interestingly, conservative justices Antonin Scalia and Anthony M. Kennedy joined Brennan’s majority, while the relatively liberal justice John Paul Stevens wrote a dissent. Flag burning was an emotional issue for the justices. Justice Kennedy wrote separately to note that his vote to protect flag burning was taking a “personal toll” on him, while Chief Justice William H. Rehnquist wrote in the primary dissent that the government had a “unique” interest in preserving the flag as a symbol of patriotic sacrifice, national harmony and American ideals.

The public was outraged, and feelings ran high. Legislators from both parties pushed for a constitutional amendment that explicitly exempted flag burning from First Amendment protections. As a delaying tactic, Democratic congressional leaders ushered through a federal flag-burning bill that made it a federal offense to desecrate the U.S. flag. While President George H.W. Bush signed the bill, the court later struck down the law. For good measure, Congress also passed a resolution condemning the court’s decision, which nearly every member of Congress could happily endorse.

Public opinion has changed

When the court took up this issue during the first Bush presidency, the public overwhelmingly favored making it illegal to burn the U.S. flag, but survey respondents rarely indicated that the issue was among the most important facing the country or would affect their vote at the polls. The constitutional amendment that seemed hard to stop in 1989 could no longer command the congressional supermajority needed for passage. Politicians still try to make political hay out of the issue, but a smaller and smaller fraction of the public say they would support a constitutional amendment to prohibit flag burning. Notably, the issue has become more partisan over time, with Democrats and liberals increasingly aligned against it. As usual, Trump is playing to his base, but he is unlikely to find the same kind of broad public support for very powerful laws against flag burning now that he could have found three decades ago.

Trump has suggested that the court is “different” today and would be more willing to uphold a flag-burning law. He is almost certainly wrong. Back then, four justices wanted to uphold such laws, including the left-leaning Stevens, centrist Democratic-appointed Justice Byron R. White, and Republican-appointed Justice Sandra Day O’Connor.

None of the current justices were on the bench in 1990, but it seems very doubtful that there are even four votes to be found on the current court to uphold a revived flag-burning statute. When the Roberts court heard a case involving the notorious Westboro Baptist Church’s picketing of the funerals of fallen soldiers, only Justice Samuel A. Alito Jr. thought such demonstrations were beyond the constitutional pale. Chief Justice John G. Roberts Jr. favorably cited the Texas flag-burning case in writing the court’s opinion protecting the picketers.

The Roberts court has ruled similarly on other cases, including the Stolen Valor Act (which sought to prohibit people falsely claiming to have won military honors); a federal statute banning videos depicting animal cruelty; and state restrictions on the sale of violent video games. When the Roberts court struck down a provision of the federal Lanham Act that excluded trademarks that disparaged people, beliefs or national symbols, no one dissented. Notably, conservative justices have often favorably quoted the flag-burning cases in their opinions.

A justice or two on the current court might think that the national interest in preserving the U.S. flag from desecration outweighs the general principle that dissidents’ expression of their beliefs should be protected no matter how unpopular their message. But outlawing flag burning would take more than one or two justices. Trump’s confidence that the justices would be in his corner may well be misplaced.

Keith E. Whittington is the William Nelson Cromwell professor of politics at Princeton University and the author of “Repugnant Laws: Judicial Review of Act of Congress from the Founding to the Present” (University Press of Kansas, 2019).