Rihanna has been subpoenaed to appear in court to testify in the assault case against Chris Brown.

"Rihanna was served at my office by L.A. DA investigators," the performer's attorney Donald Etra tells People magazine. "If the preliminary hearing indeed goes forward, she is now legally required to be there, she will be there, and will answer all questions truthfully."

The purpose of the June 22 hearing is to determine if there's enough evidence to bind Brown over to trial. The 21-year-old singer will also be subject to cross-examination by Brown's attorney Mark Geragos. The case could end any time with a plea deal, making the hearing unnecessary.

"Rihanna's testimony can make or break the case," L.A. criminal defense attorney Jeffery Rubenstein tells People. Rubenstein is not involved with the case, but adds, "Her willingness to testify and be truthful about what happened is a step closer to convicting Brown. On the other hand, if prosecutors fail to present a case, Geragos can seek to dismiss or reduce the charges on the spot."

Brown, 20, pled not guilty to two felony counts following his alleged Feb. 8 assault on Rihanna.