Theresa Owens, 49, is charged with driving under the influence of a controlled substance and possession of methamphetamine.
In December, Owens was found mentally competent to stand trial. But a second doctor expressed the opinion that the defendant was incompetent and couldn't assist her attorney.
After hearing testimony from doctors, a jury will decide if Owens is mentally competent to stand trial.
Owens allegedly drove the wrong way on a one-way road about 6:30 p.m. last Aug. 12, plowing into a group of 16-20 cyclists, hitting 10 of the riders head-on, according to Deputy District Attorney Jessica Coto.
The defendant got out of her car and appeared to be under the influence of drugs, screaming and acting erratically, according to witnesses. She was taken to a hospital, where a baggie of methamphetamine was found in a body cavity, the prosecutor said.
One of the cyclists, Juan Carlos Vinolo, was left permanently paralyzed from the waist down.