advocate

Someone whose job is to speak for someone's case in a court of law; a counsel.

Anyone who argues the case of another; an intercessor.

A person who speaks in support of something.

To plead in favour of; to defend by argument, before a tribunal or the public; to support, vindicate, or recommend publicly.

To encourage support for something.

"I like trees, but I do not advocate living in them."

(with for) To engage in advocacy.

"We have been advocating for changes in immigration law."