In a public appearance this week at The Atlantic Festival—a conference during which leaders in technology, business, politics, and arts share ideas—Sen. Jeff Flake characterized Judge Brett Kavanaugh’s recent testimony before the U.S. Senate Judiciary committee as “sharp and partisan.” He added, “We can’t have that on the [Supreme] Court.”

Sen. Flake is absolutely right.

Following Dr. Christine Blasey Ford’s powerful testimony in which she asserted that Kavanaugh sexually assaulted her when the two were in high school, Kavanaugh addressed the committee and claimed her testimony was a political hit job.

“This whole two-week effort has been a calculated and orchestrated political hit, fueled with apparent pent-up anger about President Trump and the 2016 election,” Kavanaugh said. “Fear that has been unfairly stoked about my judicial record. Revenge on behalf of the Clintons, and millions of dollars in money from outside, left-wing opposition groups.”

Apart from the serious and credible allegations of sexual assault, Kavanaugh’s partisan and remarkably injudicious testimony render him unfit to be a federal judge, let alone a U.S. Supreme Court justice.  

The Code of Conduct for United States Judges requires that judges “act at all times in a manner that promotes public confidence in the integrity and impartiality of the court.” Kavanaugh showed disregard for this all-important principle.

For years, there have been charges that the confirmation process for U.S. Supreme Court justices has become too partisan, with real costs to the legitimacy of the court itself. But never before has the nominee tainted the process, and thus the court, with such an expressly partisan statement.

If the U.S. Senate confirms Kavanaugh, how will his clearly expressed feelings about the “opposition” affect the legitimacy of decisions he may issue relating to “left-wing” organizations? He will surely be asked to consider cases about gerrymandering, voting rights, and campaign finance. What about cases brought by Planned Parenthood or the NAACP Legal Defense and Education Fund, which have opposed Kavanaugh’s nomination from the outset? Or my own organization, the American Civil Liberties Union, which recently announced its opposition to his appointment?

These questions are so serious that for only the fourth time in the ACLU’s nearly 100-year history the board of directors voted to oppose a U.S. Supreme Court confirmation. We have high standards for a lifetime appointment, and so should our elected leaders.

It is understandable that Kavanaugh would passionately defend his innocence in the face of allegations he believes to be untrue. But what we saw last week was not passion. It was partisanship.

Our rule of law depends on our faith in the system, a belief in the process despite its flaws. If the U.S. Senate confirms Kavanaugh, his unprecedented partisan testimony will jeopardize the integrity of the court.

If Sen. Flake really believes that overt partisanship must not taint the U.S. Supreme Court, he should vote no on Kavanaugh’s confirmation.