Britney Spears has been "strongly advised" to attend a custody hearing today.

"Absolutely she's been advised to show," the source says. "Her attendance is important."

The hearing is expected to focus on the four-hour standoff at her Studio City home on Jan. 3. Police, firefighters and paramedics will testify in a Los Angeles courtroom as to what occurred that night, which ended with Spears's forced hospitalization, PEOPLE reports

Spears, 26, and ex-husband Kevin Federline, 29, are not required to show, but, "Britney needs to be there because it's much easier to defend your client if he/she is present to refute what witnesses say," says L.A. family lawyer Scott Weston, who's not involved with the case.

"Whether she takes the stand or not depends on what witnesses say, and whether or not her lawyers think her testimony may backfire," Weston adds. "But they've got nowhere to go but up at this point. Also, if she doesn't attend, it shows a lack of interest on her part in getting back her kids."