system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why did Leia think it remotely plausible to claim they were on a diplomatic mission?

She tells Vader they were on a diplomatic mission. He doesn't believe her. Then in Rogue One we find out why. Because he literally followed her from a battlefield. 

How did she think this defense would be even remotely plausible?
gpt
They aren't the only Corellian Corvette in existence and it's not like they have license plates. She was basically denying that they were the one on that battlefield.

Yeah it was a weak excuse but a weak excuse is better than none and she wasn't even trying to convince Vader but rather was threatening to cause trouble for him with the Senate.