The law starts on an experimental basis in four counties - Alameda, Los Angeles, Sacramento and Tulare. The experiment phase will last five years, after which lawmakers can consider expanding the program statewide.
Supporters say it does allow people convicted of drunk driving to still use their cars. It lets them go to work, go to school, go anywhere they want to go. It just requires them to go sober.
"I think it is a great idea," said Teri Craft of Pasadena. " I think if people are drinking and driving I do not think the cost can be high enough."
"Safety is more important than anything else," said Mae Dominguez of Pasadena. "I think the laws are fair."
Opponents argue that this new system is very expensive. Most offenders will be required to pay about $125 to install and $60 monthly to maintain the device, although there is a program for low-income convicts.
First-time offenders will be required to have the devices installed for five months. A second DUI extends the requirement to 12 months, a third offense to 24 months and a fourth conviction to 36 months. The time periods double if the offense results in an injury.
The interlock law is among several taking effect July 1, the first day of the state's new fiscal year. Others include:
- A law will let repeat drunken drivers apply for restricted licenses after a 90-day suspension if they install ignition interlock devices on their vehicles.
- California is replacing a 6 percent sales tax on gasoline with a 17.3 cent per gallon excise tax. The complex gas-tax swap is part of a $4 billion plan to start addressing the state's $19 billion budget deficit. The excise tax will be used to pay off a transit bond, which means more general fund money can be spent on state services.
- A bill makes it a misdemeanor to sell or give nitrous oxide - commonly known as laughing gas - to anyone under 18. Businesses that violate the law a second time could lose their business licenses for a year. The bill's sponsor has said abusive use of inhalants can cause brain damage.
- Newly certified emergency medical technicians must submit fingerprints and other information so they can undergo state and federal criminal background checks. The bill exempts those who are certified as EMTs.
The Associated Press contributed to this report.