[ I ] UK通过非正式背景说明活动来否定/支持（人或事件），吹风否定/支持（人或事件）
to make information about someone or something public, with the intention of criticizing/praising him, her, or it
On several occasions government officials briefed against their own ministers. 政府官员曾数次以情况通报的方式批评部长们的做法。
She has been repeatedly briefed against in the media.
He dismissed the claims as rubbish and insisted that no one had briefed against him.
Smith was subsequently accused of briefing against the former leader and her allies.
It later became clear that members of the party had briefed in favour of a public judicial inquiry.
See also: brief verb