While the state of California does allow visitors over the age of 18, who have a valid driver license from their home state or country, to drive in this state without getting a California driver license as long as your home state license remains valid if your mother a CA resident she will need to obtain a California driver's license and turn in her Colorado license to the CA Department of Motor Vehicles (DMV).

According to the CA DMV if you take a job here or become a resident, you must get a California driver license within 10 days. Residency is established by voting in a California election, paying resident tuition, filing for a homeowner's property tax exemption, or any other privilege or benefit not ordinarily extended to nonresidents.

We have heard of people getting ticketed by law enforcement for driving on their previous state's license after living in California as a resident beyond the 10 days permitted by the CA Vehicle Code (VC). This citation for a driver's license offense is written up as a violation of 12500(a) of the VC meaning the individual is being cited for being unlicensed.

Basically what the CA laws say is that if you are traveling through or visiting the state of California then your out of state license, for example your mother's license from Colorado, would be accepted as a valid license to drive on. But once you move here and become a resident you need to obtain a CA driver's license to be legal to drive. Not doing so makes a driver just as unlicensed in CA as someone who just never goes to DMV to get one in the first place in the eyes of law enforcement.

A person can be written up for a violation of 12500 VC as either an infraction or a misdemeanor. The infraction usually comes with a maximum fine penalty of $250 while a misdemeanor charge comes with penalties of 6 months in jail and/or a fine of up to $1000.

From our research it seems likely that your mother would be written up for an infraction (though it really would depend upon the discretion of the law enforcement officer to cite her for an infraction or misdemeanor) which when she got her California license she may be able to have the citation dismissed in court. Or she may get her CA license before the court date but still be found guilty in court and have to pay the fine and associated court and administrative fees.

To save herself from getting a ticket and facing penalties which range from hundreds to thousands of dollars in fines to jail time she should change over her CO driver's license to a CA one within the allotted time. The California DMV notes that to not have to spend as much time waiting you can make an appointment with your local DMV to come in and get it taken care of. The DMV also gives information on what documents, tests, etc your mother will need to do in order to be given a California driver's license.