It is widely known that Donald Trump is being sued, including in class-actions—by thousands of people who charge that he defrauded them of millions of dollars. But there seems to be public confusion about how these lawsuits might affect the presidential campaign. Despite what Mr. Trump says, it appears likely that he will be called to the witness stand before the November election.

Trump University, a series of business courses that sold for up to $35,000, is the subject of three separate lawsuits, one in New York and two in California, all of which rely on the same general facts. One of these cases is likely to go to trial before the election, validating Sen. Ted Cruz’s warning during the March 3 debate that “if we nominate Donald, we’re going to spend the spring, the fall, and the summer with the Republican nominee facing a fraud trial.”

Mr. Trump makes two arguments in rebuttal. First, he scoffs at the merits of the complaints, proclaiming that “we will win in court.” Second, he suggests that nothing of importance will happen in the lawsuits until long after the election. During the same Detroit debate he admonished viewers to wait to “see what happens,” which he assured would be “at the end of a couple years.” If Mr. Trump was implying that he would not be forced from the campaign to defend himself in court, the odds are that he is wrong.

Two of the lawsuits are unlikely to be tried until after the election. The suit filed by New York Attorney General Eric Schneiderman is in the early stages of litigation and may not go to trial for years. The second case, Cohen v. Trump, a class-action pending in federal district court in San Diego, is closer to trial. That case involves claims that Mr. Trump’s alleged frauds violated federal racketeering law. But court filings suggest it may not reach trial until late 2016 or even 2017.

But the third lawsuit, Makaeff v. Trump University, also filed in federal court but with claims based upon state law, seems almost certain to go to trial this summer or fall, at the height of the 2016 campaign. The trial date won’t be set before the final pretrial conference on May 6, but Judge Gonzalo P. Curiel already has signaled his intent. Last November he denied a request to consolidate Makaeff and Cohen for trial. A primary reason was that Makaeff was closer to being ready, and “consolidating the cases presents a significant risk of further delays . . . with any trial not occurring until the early months of 2017.” In the same order, Judge Curiel declared that “any factual findings made by the jury in any trial in Makaeff conducted in the spring or summer of 2016” would be available for use later in Cohen.