She was not under arrest, nor suspicion of any wrongdoing. While her boyfriend was failing his field sobriety test, she said she wanted to apply some lip balm and so handed her purse over to the cop to check it before she would be allowed to delve into it. Cocaine fell out.
Unless you buy the explanation that it wasn't her purse, even though all of its contents - save the baggy of whizz - was hers, she is one dumb bint.