Britney Spears arrives at a recording studio in Hollywood with baby Sean Preston (05/12/06)

She cited California Vehicle Code 27360, requiring that "all children under the age of 6 or weighing less than 60 pounds be in safety seats in the back seat of the car," Zelnik said in a statement Tuesday. "Having a child in the child safety-seat facing forward in the rear seat of the car is in compliance with California law."

But Marshall said the code contained "a bit of a gray area."

"The vehicle code doesn't say you have to have the baby seat in a rear-facing position," but does maintain following federal guidelines, he said. "The bottom line is that if an officer saw her, one officer could have said it was no problem, and another could have given her a citation."

In February, authorities visited Spears' home after photos showed her driving in a car with the baby on her lap, rather than in a safety seat as required by law. Spears later apologized, saying she held the boy because of an encounter with paparazzi.

Spokesman Mike Marando of the California Office of Traffic Safety said Spears, if anything, was "breaking the spirit of the intent of the law, which is keeping the child alive."

It's more dangerous in the case of a collision to seat infants facing forward in the rear of the vehicle, he said.

Other complications remain.

Car-seat manufacturers have varied instructions on the proper use and positioning of car seats, based on the weight of the child, said CHP spokeswoman Fran Clader.

Some recommend forward-facing seats, and some recommend rear-facing seats.

"I can safely say that 90 percent of folks are not using child car seats properly," she said. "If the public has any questions, they can make an appointment with a CHP office, including Britney Spears."