When the courtroom's rockin', the gavel won't be a knockin'! Los Angeles experienced a 5.4 earthquake yesterday -- while Judge Judy was in the middle of a taping!

Judy's courtroom shook back and forth as everyone -- including the arguing parties -- ran for cover! But the defendant didn't get off that easily -- "Extra" has learned that after 45 minutes, all involved in the courtroom conflict picked up where they left off.

Now, the good judge is laying down the law -- ordering that everyone in her courtroom learn the ins and outs of earthquake safety.