I guess all [someone] can do is point out that there is precedence for [taking some action].That statement was part of an online discussion, and is an example of an error I very often see. And so, today I shall rant not about King George's latest attempt to assert excessive power, nor even about the head-butt and its cosmic effects, but on a bit of linguistic peevity.
"Precedence" means, approximately, priority. We say that "[a] takes precedence over [b]" if we prefer [a] to [b], if we put [a] before [b]. It defines a state, a preference, or a question of protocol. "In setting the agenda, we must give precedence to the Secretary of the Internal Exterior over the Vice-Assistant Undersecretary for Farmland Measurement."
"Precedent" means something that happened before, which can be used as an example in dealing with something later. "We aren't sure whether we can fire Mr Arbusto for his actions in yesterday's meeting, but the exit of Mr Milhouse from the company some years ago set a precedent that might guide us."
The correct word in the discussion quoted above would have been "precedent".