What is the meaning of the phrase "badly lit" in the following scene from the TV series Columbo (emphasis mine):
[Set in a court of law. Prosecution is attempting to prove their client was injured falling down some stairs because they did not have adequate lighting.]
Prosecution Lawyer: The plaintiff alleges the stairs were badly lit.
Defence Lawyer: Although the plaintiff may well have been!
(Laughter all around)
It seems from the context that the phrase is being used to mean "drunk". If so, is this a common use. I've certainly never heard it before.