Britney Spears had some run-ins with the law over custody of her kids and her erratic behavior, but while she was forcibly put on a psychiatric hold, she wasn't technically arrested.
Madonna's been threatened with arrest before (by Canadian police, for simulating masturbation during a concert), but she's never actually been arrested.
Whoopi Goldberg is rather public in her appreciation of marijuana, but she's never served any time for that or any other infraction.
She loves wacky antics and being nearly nude in public, but Lady Gaga has never had any real run-ins with the law.
Robin Williams has been open about his struggles with alcohol and drugs, yet he managed to always evade the law.
Zac Efron's trip to rehab for substance abuse came as a huge shock—mostly because he had never been arrested or shown any signs of struggling before that!
Vanessa Hudgens has had her share of scandals at a young age—with both nude photos and alleged drug use—but she's never been locked up.
Chelsea Handler's books chronicle her crazy history of drugs, alcohol, and wild sex, but she's managed never to be arrested.
Miley Cyrus twerks, she sticks out her tongue, she upsets old people, but she obeys the laws of the land.