As Jesse Walker noted this morning, Donald Trump thinks flag burning should be criminalized, notwithstanding two Supreme Court decisions saying such expressive activity is protected by the First Amendment. Both rulings were joined by Antonin Scalia, the late justice whom Trump says he wants to replace with someone similar.

"Nobody should be allowed to burn the American flag," Trump tweeted. "If they do, there must be consequences—perhaps loss of citizenship or [a] year in jail!" Asked about the comment on CNN, Trump spokesman Jason Miller denied that such a policy would be unconstitutional. Flag burning "is terrible and it's despicable," Miller said. "It absolutely should be illegal."

The idea that an act of protest could be offensive but nevertheless legal is apparently beyond Trump's limited understanding of the Constitution. But in the 1989 decision Texas v. Johnson, five members of the Supreme Court, including Scalia and Anthony Kennedy as well William Brennan, Thurgood Marshall, and Harry Blackmun, ruled that the First Amendment precluded criminal punishment of Gregory Lee Johnson for burning a U.S. flag during the 1984 Republican National Convention in Dallas. "Johnson was convicted for engaging in expressive conduct," Brennan wrote for the majority. "The State's interest in preventing breaches of the peace does not support his conviction because Johnson's conduct did not threaten to disturb the peace. Nor does the State's interest in preserving the flag as a symbol of nationhood and national unity justify his criminal conviction for engaging in political expression."

The following year, in U.S. v. Eichman, the same five justices overturned the Flag Protection Act of 1989, which Congress passed in response to Johnson. "Government may create national symbols, promote them, and encourage their respectful treatment," Brennan wrote. "But the Flag Protection Act of 1989 goes well beyond this by criminally proscribing expressive conduct because of its likely communicative impact. We are aware that desecration of the flag is deeply offensive to many. But the same might be said, for example, of virulent ethnic and religious epithets, vulgar repudiations of the draft, and scurrilous caricatures [all of which the Court had deemed protected by the First Amendment]. 'If there is a bedrock principle underlying the First Amendment, it is that the Government may not prohibit the expression of an idea simply because society finds the idea itself offensive or disagreeable.' Punishing desecration of the flag dilutes the very freedom that makes this emblem so revered, and worth revering."

Scalia later cited the flag burning cases to illustrate how his textualist approach to constitutional interpretation sometimes led him to rule against his personal inclinations. "If it were up to me, I would put in jail every sandal-wearing, scruffy-bearded weirdo who burns the American flag," he said in a speech last year. "But I am not king."

The idea that justices should not simply vote according to their tastes or policy preferences seems foreign to Trump, who in a debate with Hillary Clinton last month promised that "the justices that I'm going to appoint will be pro-life" and will therefore vote to overturn Roe v. Wade. Not that Clinton, despite her legal training and years in public office, was necessarily preferable to Trump on constitutional grounds. She also seemed to view justices as legislators in black robes, arguing that they have an obligation to "represent all of us," oppose "powerful corporations and the wealthy," and stop "dark, unaccountable money" from "distorting our democracy."

Clinton even tried to ban flag burning after the Supreme Court had ruled against such laws twice. Like Trump, she thought a year in jail would be an appropriate punishment. Then again, Clinton did not suggest that flag burners should lose their citizenship—a penalty the Supreme Court has said Congress is not authorized to impose.