Legal Question in Criminal Law in California

Yes. A petty theft can (but need not) be a felony if the defendant was previously convicted of a petty theft or certain other types of theft and if he was jailed or imprisoned as a result.

Petty theft with a prior is governed by Penal Code section 666, which says:

"Every person who, having been convicted of petty theft, grand theft, auto theft under Section 10851 of the Vehicle Code, burglary, carjacking, robbery, or a felony violation of Section 496 and having served a term therefor in any penal institution or having been imprisoned therein as a condition of probation for that offense, is subsequently convicted of petty theft, then the person convicted of that subsequent offense is punishable by imprisonment in the county jail not exceeding one year, or in the state prison."

We call it a "petty with a prior." The prior does not have to be a felony. The fact that you have a prior makes the new one a felony.

For the benefit of other users:

Penal Code section 666 has just been amended. In some circumstances, it now takes three or more prior convictions to boost a misdemeanor petty theft to a felony.

The changes went into effect yesterday (September 9, 2010). They won't help the user who posted this question, but they may help others in the future.