FWIW, I did that--5 (Instant) with "(do not web search)" tacked on--and it thought the case was real:

> Based on my existing knowledge (without using the web), Varghese v. China Southern Airlines Co. is a U.S. federal court case concerning jurisdictional and procedural issues arising from an airline’s operations and an incident involving an international flight.

(it then went on to summarize the case and offer up the full opinion)