The Senate this week rejected the nomination of Debo Adegbile, a former Supreme Court advocate for the NAACP Legal Defense Fund, to lead the Justice Department’s civil rights division.

Sen. Chris Coons, D-Del., one of those who voted no, immediately admitted that the vote wasn’t about the nominee’s ability to do the job. Rather, it was because of Adegbile’s limited association with the case of Mumia Abu-Jamal, an inmate convicted of killing a Philadelphia police officer.

“As a lawyer, I understand the importance of having legal advocates willing to fight for even the most despicable clients, and I embrace the proposition that an attorney is not responsible for the actions of their client,” Coons said. “The decades-long public campaign by others, however, to elevate a heinous, cold-blooded killer to the status of a political prisoner and folk hero has caused tremendous pain to the widow of Philadelphia police officer Daniel Faulkner and shown great disrespect for law enforcement officers and families throughout our region.

“These factors have led me to cast a vote today that is more about listening to and respecting their concerns than about the innate qualifications of this nominee.”

But Adegbile’s innate qualifications were the issue. In his vote and follow-up statement, Coons betrayed the ethical principles on which the justice system depends, acknowledged his hypocrisy and repudiated another crucial principle: that the president should be able to staff his administration with appointees of his choosing unless they are sorely unqualified.

The Senate’s habit of turning confirmation votes into proxy wars hurts the country. It deters many people from public service, and it makes staffing the government outrageously time-consuming. One can be sympathetic to Faulkner’s family and dismissive of the movement to valorize his killer without hijacking our system of checks and balances to make that point.

Stephen Stromberg is an editorial writer for The Washington Post.