Britney plans to go to court today with her lawyers to ask the judge to expand her visitation rights to overnight visits with her kids. We're told Spears was urged by her lawyers to attend the hearing, scheduled for 8:30 AM in downtown Los Angeles.

We've also learned Spears has now had several clean drug tests. Brit's lawyers will use the these tests and other evidence to make their case. They've told Britney her presence will show the judge how much she cares about the kids-- she finally gets it and plans to show.

[tmz]