Penal Code section 666 lets a new petty theft be charged as a wobbler, reaching state prison, but only for someone who must register as a sex offender, has one of a short list of serious priors, or has a qualifying elder abuse conviction. Without one of those three specific priors, an ordinary petty theft prior does not trigger Section 666; a different statute, Section 666.1, may still apply.
The three specific priors that trigger Section 666
Penal Code section 666(a) applies to a person previously convicted of petty theft, grand theft, auto theft, burglary, carjacking, robbery, felony receiving stolen property, or certain elder theft, who served time for it, and is later convicted of petty theft again, but only if that person also falls into one of three categories listed in subdivision (b): a person required to register as a sex offender, a person with one of the specific prior felonies that Penal Code section 667(e)(2)(C)(iv) separately lists, a short specific list such as a sexually violent offense, any homicide offense, solicitation to commit murder, or assault with a machine gun on a peace officer, and not the broader serious-or-violent-felony definition used elsewhere in the Three Strikes law, or a person with a qualifying elder abuse conviction. All three conditions, the qualifying prior theft offense, time served, and one of these three categories, have to be true together. "Served time for it" matters on its own; a person who received straight probation on the prior theft offense, without any jail or prison time, may not satisfy that part of subdivision (a) even if the prior offense and one of the three categories both check out, which is a separate and often overlooked requirement.
Why most petty theft priors do not qualify, since Proposition 47
Before California voters approved Proposition 47 in November 2014, almost any prior theft conviction was enough to charge a new petty theft as a wobbler under Section 666. Proposition 47 narrowed the statute to the three categories above, so a person with an ordinary record of old petty theft or shoplifting convictions, without a violent or serious felony, a sex offense registration requirement, or a qualifying elder abuse conviction, generally cannot be charged under Section 666 for a new petty theft today, even with several old theft priors on their record.
What the penalty actually is
Section 666 is a wobbler. It is punishable by "imprisonment in the county jail not exceeding one year, or in the state prison," though Penal Code 18.5 caps that actual county jail exposure at 364 days, and where the court imposes a state prison term without a length written into the statute itself, the default felony term under Penal Code section 1170(h) is 16 months, two years, or three years. Subdivision (c) also makes clear that Section 666 does not stop the case from being prosecuted and punished as a strike under the Three Strikes law where the underlying priors qualify.
How this differs from Penal Code 666.1
A separate statute, Penal Code section 666.1, reaches more ordinary repeat offenders: it applies to someone with two or more prior convictions for petty theft, grand theft, theft from an elder or dependent adult, vehicle theft, burglary, carjacking, robbery, receiving stolen property, shoplifting, identity theft, or mail theft, without also needing a sex offense registration or one of Section 666's own narrow qualifying prior felonies. Someone whose record is mostly old theft and shoplifting cases, rather than a violent or serious felony, is far more likely to actually be facing Section 666.1 than the narrower Section 666, even if the charging paperwork or a plea offer calls it only "petty theft with a prior." Both statutes include a savings clause making clear that a conviction here does not block separate Three Strikes prosecution or punishment based on a defendant's own independently qualifying priors: subdivision (c) of 666 refers specifically to Section 667(b) to (i) and Section 1170.12, and subdivision (d) of 666.1 refers to any other law. Neither statute makes the petty theft conviction itself a strike.
How the prosecution has to prove the prior itself
Charging someone under Section 666 is not enough on its own; the prosecution has to prove the specific prior conviction actually happened and that it falls within one of the three qualifying categories, typically through a certified record of conviction rather than a police report's summary of someone's record. The defense can dispute whether a particular older conviction actually appears on the short, specific list of prior felonies that section 667(e)(2)(C)(iv) names for this purpose, since an ordinary serious or violent felony, such as robbery or residential burglary, does not by itself qualify, or whether a registration requirement or an elder abuse finding was ever actually entered on the earlier case. A certified record that turns out to describe a different offense, a different person, or a conviction that was later reduced or vacated can remove the basis for a 666 charge entirely, even where a new petty theft itself is not in dispute.
What to check first if you are told you face a 666 charge
Pull the exact prior conviction the current charge is based on and compare it against the three categories in subdivision (b), not just whether it was a theft case. A prior for ordinary petty theft, without a registration requirement, a violent or serious felony, or qualifying elder abuse, is not on its own enough for Section 666, whatever the citation or complaint calls it. If the paperwork is unclear about which category the prosecution is relying on, that ambiguity itself is worth raising before entering any plea, since a mistaken 666 charge can otherwise be accepted as though it were valid, carrying consequences a correctly charged misdemeanor or a 666.1 case would not have carried.
The firm's page on petty theft with a prior covers how these enhancement cases, including Section 666.1, are typically defended.