The past participle proven, originally the past participle of preve, a Middle English variant of prove that survived in Scotland, has gradually worked its way into standard English over the past three and a half centuries. It seems to have first become established in legal use and to have come only slowly into literary use. Tennyson was one of its earliest frequent users, probably for metrical reasons. It was disapproved by 19th century grammarians, one of whom included it in a list of “words that are not words.” Surveys made some 50 or 60 years ago indicated that proved was about four times as frequent as proven. But our evidence from the last 30 or 35 years shows this no longer to be the case. As a past participle proven is now about as frequent as proved in all contexts. As an attributive adjective <proved or proven gas reserves>proven is much more common than proved.
Examples of PROVE
The charges against him were never proved in court.
The government failed to prove its case.
It could not be proven that the suspect stole the money.
A person who is charged with a crime is considered innocent until proved guilty.
mathematicians trying to prove a theorem
To prove her point, she got out the old research.
The tests proved the vaccine to be effective.
Her second album was a hit that proved her critics wrong.
Origin of PROVE
Middle English, from Anglo-French prover, pruver, from Latin probare to test, prove, from probus good, honest, from pro- for, in favor + -bus (akin to Old English bēon to be) — more at pro-, be