Both Uses

advocate
in
Slaughterhouse-Five
(Edited)

Billy read the opinion of a staff judge advocate who reviewed Slovik's case, which ended like this: He has directly challenged the authority of the government, and future discipline depends upon a resolute reply to this challenge.†
Chpt 2 *

advocate = a lawyer or officer of the court in some jurisdictions in Europe, colonial America, and the military
The advocates of nuclear disarmament seem to believe that, if they could achieve their aim, war would become tolerable and decent.
Chpt 9 *

advocates = people who publicly support

Definitions:

(1) (advocate as in: to advocate)
to recommend or publicly support (someone or something)
(2) (advocate as in: an advocate supporting)
a person who publicly supports and works to advance a cause

or more rarely:

someone acting in the role of a defense lawyer in England's past and in some jurisdictions today
(3) (advocate as in: an advocate in court)
a lawyer or officer of the court in some jurisdictions in Europe, colonial America, and the military
(4) (devil's advocate as in: I'll play the devil's advocate)
a person who takes an unpopular position to encourage debate or test ideas
(5) (meaning too rare to warrant focus)