无效

This cheque is null and void.

The contract is invalidated/invalid if only one party signs it.

The high court declared the trial a mistrial.

The contract will not stand. / This contract is of no effect.

invalid passport

inert drug/medicine; ineffective medicine

terminate an invalid contract

be invalid after the specified/expiry date

fail to respond to medical treatment; medical treatment proves ineffective; all medical efforts are of/to no avail

nullify an election

declare a contract invalid; invalidate/nullify a contract

consider a contract null and void