Civil liberties lawyer and prominent liberal Alan Dershowitz said he sees no evidence that President-elect Donald Trump’s White House appointee Stephen K. Bannon is anti-Semitic.

Mr. Trump’s chief strategist pick of Mr. Bannon, the former executive chairman of Breitbart News, has been criticized by foes of the conservative website. The Anti-Defamation League said it “strongly” opposed the appointment and painted Mr. Bannon as the leader of the alt-right movement, which it described as a “a loose-knit group of white nationalists and unabashed anti-Semites and racists.”

Mr. Dershowitz advised people to be “very careful” about accusing others of being anti-Semitic.

“The evidence certainly suggests that Mr. Bannon has very good relationships with individual Jews,” the Harvard law professor told Breitbart News reporter Aaron Klein. “My former researcher, [Breitbart News Senior Editor-at-Large] Joel Pollak, is an Orthodox Jew who takes off the Jewish holidays, who is a committed Jew and a committed Zionist, and he has worked closely with him. He has been supportive of Israel.

“So, I haven’t seen any evidence of personal anti-Semitism on the part of Bannon,” he said. “I think the larger problem — and it’s a very complicated one today — is how you assess a person who himself might not have negative characteristics, but who has widespread appeal to people who do. And I think that problem exists on the right and the left.”

Mr. Dershowitz agreed that the claims of anti-Semitism against Mr. Bannon devalued the term.

“One, I don’t think anybody should be called or accused of being anti-Semitic unless the evidence is overwhelming,” he said. “And then the second, more subtle and difficult issue is what about characterizing supporters or people who follow them? Subtle distinctions have to be made.”

Mr. Pollak has staunchly defended his former boss, writing in a column Monday that Mr. Bannon is “a friend of the Jewish people and a defender of Israel, as well as being a passionate American patriot and a great leader.”

“I am an Orthodox Jew, and I hold a Master of Arts degree in Jewish Studies. My thesis at the Isaac and Jesse Kaplan Centre at the University of Cape Town dealt with the troubled status of Jews in an increasingly anti-Israel, and anti-Semitic, post-apartheid South Africa. I believe myself to be a qualified judge of what is, and is not, anti-Semitic,” Mr. Pollak argued. “Steve is outraged by anti-Semitism. If anything, he is overly sensitive about it, and often takes offense on Jews’ behalf.”