Supreme Court Justice Brett Kavanaugh voted against abortion rights precedent the court had set just four years earlier — breaking a promise Sen. Susan Collins (R-ME) said he had made in order to gain her confirmation vote.

During the confirmation process, Collins said she decided to vote in favor of Kavanaugh because he told her he believed "the concept of precedent is rooted in Article III of the Constitution" — and she said that meant he wouldn't vote to overturn abortion rights.

"He also believes that it is not sufficient — since I asked him this directly — for five sitting judges to believe that an earlier decision was incorrectly decided. He said it would have to be grievously wrong and deeply inconsistent," Collins told Bloomberg News' Steven Dennis ahead of her vote to confirm Kavanaugh.

However, on Monday, Kavanaugh was one of four conservative justices to vote to uphold a Louisiana abortion law that would have left the state with just one abortion clinic. The Supreme Court had struck down an almost identical law in Texas just four years ago, meaning Kavanaugh voted against recent Supreme Court precedent.

Chief Justice John Roberts sided with the Court's liberal justices to vote to strike down the Louisiana law, directly citing his belief in upholding precedent.

"Today's case is a challenge from several abortion clinics and providers to a Louisiana law nearly identical to the Texas law struck down four years ago," Roberts wrote in a concurring opinion.

"The legal doctrine of stare decisis requires us, absent special circumstances, to treat like cases alike," Roberts continued, citing the Latin term for the legal principle of adhering to past precedent. "The Louisiana law imposes a burden on access to abortion just as severe as that imposed by the Texas law, for the same reasons. Therefore Louisiana's law cannot stand under our precedents."

Collins' vote to confirm Kavanaugh has dogged her 2020 reelection bid.

While Collins has glided to reelection in past cycles, her 2020 race against likely Democratic opponent Sara Gideon, Maine's current state House speaker, is fiercely competitive.

A poll from October 2019 found that following Collins' vote to confirm Kavanaugh, her approval rating in the state took a steep fall — in large part thanks to a loss of support from Democrats, who once crossed party lines to back her. The nonpartisan political handicapping outlet the Cook Political Report rates Collins' race a toss-up.

Kavanaugh's vote against abortion rights precedent now gives Democrats even more ammunition to use against Collins heading into the election.

"Once again, we have been proven right about Brett Kavanaugh and Susan Collins has been proven wrong," Brian Fallon, a Democratic strategist and executive director of Demand Justice, a progressive group that wants to "restore the ideological balance and legitimacy of the federal courts," tweeted. "Vote her out."

Published with permission of The American Independent Foundation.