in force vs operative

in force is not a noun while operative is a noun.

Word	Noun	Adjective	Verb	Adverb
in force	No	Yes	No	No
operative	Yes	Yes	No	No

in force (noun)	operative (noun)
	someone who can be employed as a detective to collect information and assist in criminal investigations
	a person secretly employed in espionage for a government

in force (adjective)	operative (adjective)
exerting force or influence	being in force or having or exerting force
	relating to or requiring or amenable to treatment by surgery especially as opposed to medicine
	(of e.g. a machine) performing or capable of performing
	effective; producing a desired effect