It was left to Florida International University law professor Elizabeth Price Foley, another witness, to remind Democrats that in fact no fewer than 44 lawsuits in which legislators sought standing had been filed in federal court since Coleman v. Miller. Of the 41 filed by plaintiffs with unified political affiliation, nearly 70% were brought by Democrats. At least 20 of those came since 2000. The GOP might thank Ms. Slaughter for the idea.

Save one crucial difference. It was also left to Ms. Foley to explain that the reason most of these prior cases had failed is because most were, in fact—again, in Ms. Slaughter’s words—”political stunts.” The majority, including the Slaughter case, were brought by ad hoc groups of legislators, sore over a lost political battle, complaining to courts. The judiciary wasn’t much impressed.

By contrast—and by far the more notable aspect of the five long hours of the hearing—is the care the Boehner team is putting into its own suit. While Democrats used Wednesday to score political points, Republicans used it to grill their expert witnesses on case law and constitutional questions. Mr. Boehner’s decisions to have the House as a whole vote to authorize the suit, and to narrowly tailor it around a specific presidential transgression (and one that no private litigant would ever have standing to protest), are designed to make this a far different and better breed of a court case.