WHEN Donald Trump recently asked his supporters in Ohio to keep an eye out for voter fraud on election day, his plea came with a knowing suggestion: “When [I] say ‘watch,’ you know what I’m talking about, right?” Mr Trump’s worry that the election will be “rigged” has inspired repeated calls for volunteers to serve as poll watchers in cities including Philadelphia, Chicago and St Louis. At a recent rally in Pennsylvania, he had this to say: “You've got to go out, and you've got to get your friends, and you've got to get everybody you know, and you gotta watch the polling booths, because I hear too many stories about Pennsylvania, certain areas”. It would be a shame, Mr Trump said, to lose the White House “because of you know what I'm talking about.”

What Mr Trump seems to be talking about is scores of black and Latino voters who are unfriendly to his candidacy and—purportedly—not eligible to vote. With little more than a hunch that “of course...large scale voter fraud” prevails in “certain communities”, Mr Trump ignores studies belying the claim. A review of 12 years of allegations turned up just 10 cases of confirmed fraud. Another study found 31 cases of voter impersonation out of a billion votes cast from 2000 to 2014. There are no signs that Democrats are coordinating a national strategy to harness voter fraud to steal the election.

But never mind the facts. Mr Trump has a link on his website where devotees wishing to “volunteer to be a Trump election observer” can sign up to receive information. “Help me stop Crooked Hillary from rigging the election!” the page implores. The Republican Party is doing little to amplify these calls, and for good reason. For years, the Republican Party engaged in widespread voter intimidation and, in 1981, the Democrats called them on it in court. In a gubernatorial election in New Jersey, the Republican National Committee (RNC) targeted racial and ethnic minority voters by, among other things, recruiting armed “off-duty sheriffs and police officers to intimidate voters by standing at polling places in minority precincts during voting with ‘National Ballot Security Task Force’ armbands”. To resolve the lawsuit, the RNC agreed to stop “engag[ing[ or assist[ing] in voter fraud prevention” without the pre-approval of a federal court. This agreement expires next year, as long as the RNC stays clean. But if the party violates the rules this fall, the decree will be extended for another eight years.

The racial overtones of Mr Trump’s appeals are hard to miss, as is their tenuous relationship with basic principles of electoral democracy. (Even former Fox News commentator Glenn Beck, no friend of the left, has compared Mr Trump's henchmen to the “brownshirts” who helped Adolf Hitler launch the Third Reich.) With the polls increasingly favouring Hillary Clinton, the drama of the race is turning to how Mr Trump’s calls will play out at polling places on November 8th. Some legal experts note that the Republican nominee’s comments are edging closer to “incitement”, a category of speech that enjoys no constitutional protection. The Supreme Court said in 1969 that a speaker who wilfully attempts to whip up a crowd to commit an imminent crime could be subject to criminal prosecution.

This standard is plagued by vagueness, making incitement quite difficult to establish. But Sonja West, a law professor at the University of Georgia, says it’s not out of the realm of possibility for the 2016 election. “Even if [Mr Trump] is only implying that his followers illegally harass minority voters, if it can be shown that he intends for them to read between the lines and it's likely they will read between the lines...there’s a good argument” for viewing his appeal as “directed to inciting law breaking”.

The trickier question concerns imminence. Even direct appeals to people to break the law enjoy constitutional protection when uttered weeks or days before the intended action. As Lyrissa Lidsky of the University of Florida notes, the standard was developed with an eye to the “on-scene mob scenario”. Only a case in which a speech stirs up immediate lawlessness qualifies. “Given enough time” between the speech and the event, she says, “the audience’s good sense” may be restored and listeners might reconsider acting on the rabble-rouser’s dictates. But if Mr Trump posted a tweet directed to crowds already intimidating voters on election day to the effect of, “It's time we took back our country. I want you to keep cheating Democrats from voting by any means necessary", Ms Lidsky says, “there's a good argument that this speech could be prosecuted as incitement...You've got an inflamed mob and no time for reason to reassert itself before serious violence can occur.” Laurence Tribe of Harvard Law School agrees that Mr Trump’s “First Amendment defence would no longer be airtight” if his campaign advocated racial harassment at “a rally in close proximity to the time and place where people were waiting to cast their ballots”.

The First Amendment has been a frequent punching bag of Mr Trump’s alarmingly litigious campaign. “It is not ‘freedom of the press’”, he tweeted in August, “when newspapers and others are allowed to say and write whatever they want even if it is completely false!” A few months earlier, Mr Trump had promised to “open up those libel laws” so that newspapers could be sued for “hit piece[s]” against public figures. And in early October, the Republican nominee threatened to sue the New York Times for a “reckless”, “inflammatory” and “politically motivated” article reporting harassment accusations against him by several women. Fortunately, presidents have no power to alter defamation law. But with the election only two weeks away, another Trump campaign tactic is testing the reach of the First Amendment umbrella.