moot point, a

moot point

A point, aspect, or topic that is no longer relevant or can no longer be questioned or debated. Whether or not he's the best person for the job is a moot point now that he's tenured. A: "Have you looked at Harvard's program?" B: "That's a bit of a moot point, don't you think? I've already accepted a place at NYU."
See also: moot, point
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

moot point

A debatable question, an issue open to argument; also, an irrelevant question, a matter of no importance. For example, Whether Shakespeare actually wrote the poem remains a moot point among critics, or It's a moot point whether the chicken or the egg came first. This term originated in British law where it described a point for discussion in a moot, or assembly, of law students. By the early 1700s it was being used more loosely in the present sense.
See also: moot, point
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

moot point, a

A debatable question. This term was originally exclusively a legal one, a moot case or moot point being a case for discussion in a moot, or meeting, of law students. By the eighteenth century, however, it was being used figuratively in a far more general way. For example, “It is a very moot point to which of those causes we may ascribe the universal dulness of the Irish,” wrote Sir C. Wogan (1732–33), cited by the OED.
See also: moot
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer
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