Allowing this symposium to proceed along the lines laid out in the announcement will be a black mark for Stanford in the scientific community.

Refusals or questioning led to the withdrawal of athletic sponsorship and a black mark against your name in Stasi files.

It was a landmark — and, for Trumpov’s supporters, a black mark — in American history.

If it met conditions negotiated with the Justice Department until Jan. 7 of this year, Boeing could avoid further sanctions and yet another black mark related to the disaster.

“That’s a black mark on the industry and on the profession.”