Of a legal act, statement, evidence, etc.: Confirmatory.

Chiefly Law. Originally Scots Law. Having the quality or function of proving or demonstrating; affording proof or evidence; demonstrative, evidential.

That nicks (in various senses of the verb).

Of a legal instrument: that confirms a claim, etc. Obsolete.

That conveys a charge or imposition.

That tends to corroborate, or has the effect of corroborating; corroborative.

Of an alibi: introduced unexpectedly at the conclusion of court proceedings, giving the prosecution no chance to rebut it. Now historical.