California had time to prepare for the legalization of recreational marijuana since voters passed Proposition 64 in November 2016. Even before that, there was legalized use of marijuana for medicinal purposes. However, California has yet to answer an important question related to recreational marijuana use: How much marijuana must a driver have in their system in order to be legally impaired? Drivers know that the legal limit for alcohol is a 0.08 blood alcohol concentration and approximately how much alcohol they can consume before they reach that limit. California drivers and police officers can only guess how much marijuana is needed to make someone legally impaired, which puts marijuana users at a disadvantage when they are trying to be safe drivers.

Uncertain Answer

To be fair, it is difficult to quantify the point at which marijuana in a person’s body impairs a driver’s function enough to be a violation of DUI laws. The scientific consensus is that tetrahydrocannabinol (THC) levels are the closest equivalent to BAC levels, but THC can linger in a person’s body for weeks after marijuana use, by which point any impairing effects have subsided. Amongst the states that have legalized recreational marijuana, only Colorado has created a THC limit. Prosecutors in that state can bring DUI charges against a driver who has five nanograms of active THC in their blood. Still, Colorado says that officers should primarily rely on observational signs of impairment when determining whether to arrest someone for DUI.

Upcoming Studies

California officials have recognized their lack of knowledge about the relationship between marijuana use and impaired driving. California recently enacted a law that authorizes the California Highway Patrol to conduct a study of the effects that marijuana has on driving. The Center for Medicinal Cannabis Research at the University of California, San Diego, is also researching driving under the influence of marijuana. Through controlled tests involving drivers with different levels of THC, researchers hope to understand:

There are several modes of transportation others than cars and trucks that are illegal to operate while under the influence of alcohol or drugs. You could be charged for being under the influence while operating a boat, riding a motorcycle, or even riding a horse. Then there is the criminal offense of cycling under the influence. Unlike many other states, California has a separate law that addresses CUI offenses. The consequences are not as severe as being convicted for driving under the influence, but it is still not a conviction that you want on your criminal record.

Charge and Penalties

The rules of a bicycle traffic stop are similar to stops involving motor vehicles:

• Police are allowed to stop anyone who they reasonably suspect may be under the influence;
• The officer will look for signs that the cyclist is intoxicated, such as bloodshot eyes, slurred speech, and lack of balance;
• The officer will ask questions to better understand the cyclist’s condition;
• The officer may arrest the cyclist if they have probable cause to believe the cyclist is legally intoxicated; and
• The blood alcohol concentration limit for a cyclist is 0.08.

Cycling under the influence is a misdemeanor offense, punishable by a $250 fine. There would be no jail time, but the conviction would remain on your criminal record. People younger than 21 who are convicted of CUI may lose their driving privileges for a year or be prohibited from applying for a driver’s license for a year.

Driving under the influence in California applies to more than just alcohol. You can be charged with DUI for being under the influence of drugs. The penalties for DUID are the same, including fines, a driver’s license suspension, and possible jail time. Many people associate being under the influence of drugs with getting high from recreational drugs such as marijuana. However, drugs can include legally prescribed and over-the-counter medicines. Police will not excuse your impaired driving simply because you have a prescription for the drug.

Side Effects

Many prescribed drugs can cause side effects that may impair a user’s ability to drive, such as drowsiness or dizziness. These medicines include:

• Pain relievers;
• Sleeping pills;
• Antihistamines;
• Decongestants;
• Antidepressants; and
• Medical marijuana.

Some people are more susceptible to these side effects than others. When starting a new medication, you should keep track of its effect on you to determine whether it is impairing your vision, motor skills, or ability to stay attentive. You should also heed warnings about mixing the prescription with alcohol because it may worsen the side effects.

The consequences of a conviction for driving under the influence can follow you across the U.S., despite the fact that the conviction originated in one state. California is one of 45 states that are members of the Driver License Compact – an agreement in which states are required to share information about convictions for traffic offenses and to enforce the punishments instituted by other states. If you are a California resident who was convicted of DUI in another state, California is obligated to enforce punishments such as a driver’s license suspension. The same obligation applies if you are a resident of another state in the DLC and are convicted of DUI in California.

California Rules

Though all members of the same compact, each state has its own laws regarding what qualifies as a DUI offense and what the punishment for a conviction will be. California will enforce other state’s DUI convictions as long as they comply with California’s own rules. California will not enforce another state’s DUI conviction if:

• The offense would not have violated California’s DUI laws;
• The other state enforces DUI laws differently than California; or
• The description of the offense does not match California’s definition of DUI.

For instance, Utah recently lowered its blood alcohol concentration limit to 0.04. California would not enforce punishment for a DUI conviction if the offender’s BAC was below 0.08.

Silence has been the prevailing wisdom when stopped by a police officer on the suspicion of a crime such as driving under the influence. By not saying anything, you avoid potentially incriminating yourself with your words. The Fifth Amendment to the U.S. Constitution gives you the right to refrain from answering a question that may incriminate you, and the Miranda Rights that police must read after your arrest starts with “You have the right to remain silent.” Defense attorneys have long argued that silence cannot be portrayed as an admission of guilt during a case. However, a California Supreme Court ruling in 2014 determined that a defendant’s silence after a DUI stop could be used against him in court.

People v. Tom

In the case of People v. Tom, the defendant was charged with gross vehicular manslaughter while intoxicated after being involved in a fatal car collision. During the trial, the prosecution mentioned that the defendant had not asked the responding police officers about the condition of the occupants of the other vehicle before his arrest. The prosecutor argued that the defendant was silent because he either knew he was guilty of DUI or had a reckless disregard for the safety of others. The jury convicted the defendant, who appealed in part because he claimed his silence should not have been allowed as evidence of his guilt. The California Supreme Court ruled that the prosecution was within its right to present that evidence because:

• The defendant had not been read his Miranda Rights at the time of his silence; and
• A suspect must expressly invoke his or her right to remain silent.

What It Means

Your right to remain silent and avoid self-incrimination is always available, but the circumstances can determine whether the court will presume that you were invoking that right. The court will look at: