Dec. 23, 2013 -- The family of an Oakland girl who was declared brain dead after a tonsillectomy is expected to appear in court today, along with hospital officials, where a judge will appoint a neurologist to re-examine the girl's condition.

Jahi McMath's family, which will hold a march and rally today, obtained an order Friday from Superior Court Judge Evelio Grillo to keep doctors at Children's Hospital Oakland from removing the 13-year-old from a ventilator.

The independent doctor, approved by the McMath family and the hospital, will perform a brain examination on the teen later today. The court- and family-approved doctor will present the findings of his or her examination to the judge Tuesday.

WATCH: Oakland Mother Fights to Keep Child, 13, Alive

Jahi was admitted to the Children's Hospital Oakland Dec. 9 to have her tonsils removed. The family says the girl bled profusely after the routine surgery. She then went into cardiac arrest before being declared brain dead Dec. 12. The hospital wanted to disconnect the girl from her life support shortly after the diagnosis, but the family attorney sought a court order to keep her alive.

In its court memorandum, the hospital said it has no duty to maintain life support because Jahi's condition is irreversible.

"Ms. McMath is dead," the hospital said in the memo. "Children's is under no legal obligation to provide medical or other intervention for a deceased person."

The family told ABC News station KGO-TV in San Francisco they will hold a march and rally later today outside the hospital. They said the rally will be peaceful and lawful.

"Jahi's favorite color is purple," her uncle Omari Sealey said. "So if you can come out wearing a purple shirt, it doesn't matter what shade it is. But if you have a purple shirt, please wear it and march with us Monday morning."

The teen's mother, Nailah Winkfield, says she cannot bring herself to take her daughter off life support.

"Despite what they say, she is alive. I can touch her, she is warm. She responds to my touch," Winkfield said in an open letter Saturday. "Given time I know (God) will spark her brain awake."

Winkfield also lashed out at the hospital, writing "They have been pressuring me to 'pull the plug.'"

"I can't. I won't. I can't let them kill my baby a second time," she added.

But the hospital says tests performed separately by a neurologist and the attending physician indicate that the girl's entire brain, including stem cells, have stopped functioning.

"Our hearts go out to this patient and her family," the hospital's chief of pediatrics, Dr. David Durand, said in a statement last week. "Unfortunately, we have not been authorized by the family to share information with the public about this matter.

"Consequently, we are not able to correct misperceptions created about this sad situation."

ABC News' Anthony Castellano and The Associated Press contributed to this report.