Britney’s back to her partying ways even though a judge has ordered that she have random drug testing.

Tuesday night Spears and Avril Lavigne were seen hitting the LA club scene. The singers were followed by a pack of paparazzi. Spears weas first spotted at Winstons with Lavigne, and then with friend Alli Sims.

The ladies left the club at about 1 am, but Spears was seen again later at the Hyde Lounge where she stayed until the club closed.

“They kept bringing (Spears) shots and so they were drinking,” says a Hyde observer. “She was dancing on the tables trying to be really sexy, even putting a black sock over her head as a hat, and putting on a show for everyone.”

Another observer saw what appeared to be alcohol in front of Spears but didn’t see her drink it.

Britney even drove to the police station at one point during the evening to complain about the paparazzi, but no action was taken.

The Judge in her custody fight with Federline found that she is “habitual, frequent and continuous” user of alcohol and controlled substances, and now must submit to random twice-weekly testing. Did this judgment tick her off and make her party more? Who knows?

Maybe she’s just getting the partying out of the way before she spends times with her kids again? Los Angeles Superior Court Commissioner Scott Gordon also ruled that both Spears and Federline may not consume alcohol or non-prescription controlled substances at least 12 hours prior to being with their children.