Forgive my question, but since I'm not familiar with the Metro system what was the problem with her having a candy bar?
There's no eating allowed on the system.
There is not food allowed in the Metro station.
IIRC, the food was in her mouth.
The cop told her not to enter with the food.
She stuffed it in her mouth then walked through the turnstyle.
Then she was arrested.
No eating on the Metro - $100 fine. I take the Blue line from the Pentagon to downtown and am always warning tourists to at least be discreet.