Validate

transitive verb
check or prove the validity or accuracy of something; demonstrate or support the truth or value of; make or declare legally valid

Eutychus pointed to the long length of the sermon to validate his deathly fall.
Tim validated falling asleep on the phone on the basis of Meredith's silly, pointless conversation :)
He had the waiter validate his parking ticket with a signature.

I like transitive verbs!