A federal lawsuit challenging the repeated cancellation of cost-of-living adjustments for congressional salaries has advanced, potentially awarding current and former members of Congress millions in back pay and leading to future salary increases. Taxpayers could be responsible for at least $69 million if the suit is decided in favor of the plaintiffs, according to an estimate from the National Taxpayers Union.

The lawsuit argues that Congress violated the 27th Amendment by repeatedly voting to repeal a 1989 law intended to keep member salaries aligned with inflation. The 27th Amendment states that "no law varying the compensation for the services of the Senators and Representatives, shall take effect, until an election of Representatives shall have intervened."

Federal Claims Court Judge Eric Bruggink ruled that the case could move forward, stating that laws varying congressional compensation are ineffective if they seek to change salaries before an election occurs. "Laws varying congressional compensation are ineffective to the extent they seek to effectuate a change in congressional compensation before an election intervenes," he wrote in his opinion.

Plaintiffs in the case include Reps. Steny Hoyer (D-Md.), Rick Crawford (R-Ark.), and James Clyburn (D-SC), along with former Reps. Rodney Davis (R-Ill.) and Ed Perlmutter (D-Colo.). Ken Cuccinelli, an attorney for the suing lawmakers, stated that their goal is to stop "continual violations of the Constitution as it relates to Congressional pay." He noted that, on an inflation-adjusted basis, congressional pay is at its lowest point since 1954.

If the judiciary rules in favor of the plaintiffs, individual lawmakers could receive between $225,000 and $420,000 in back pay. The exact number of current and former members eligible for these payments is still being determined. Beyond back pay, a successful court outcome could also lead to automatic annual salary increases for members of Congress. Estimates suggest this could raise their annual pay to over $253,000, a 45% increase from the current $174,000 salary, which has remained fixed for nearly two decades.

Members of Congress last received a pay adjustment in 2009, when their salary increased to $169,300 from $169,300, a raise of 2.8%. Since the 27th Amendment's ratification in 1992, Congress has rejected its own pay raises 21 times.

Critics, such as Demian Brady, vice president of research at the National Taxpayers Union Foundation, argue that lawmakers should seek pay raises through legislative votes rather than through the courts. "Because of all these perplexing questions, and because the damages will fall on taxpayers through higher deficit spending and potentially higher long-term liabilities, and also because of the reputational harm this will do to Congress as an institution, I’ve urged the lawmakers to drop their case," Brady said. He added, "They should seek higher pay by convincing their colleagues to vote for higher pay instead of suing taxpayers."

Supporters of the lawsuit point out that members of Congress often incur costs associated with maintaining two residences, one in their district and one in Washington D.C. If the lawsuit results in increased salaries, former lawmakers could also seek to have their pensions adjusted, adding further potential costs to taxpayers.