Being accused of being under the influence of a controlled substance under California Health & Safety Code 11550 is more common than many people realize — but it’s still a serious criminal matter with lasting consequences. This law makes it a misdemeanor to be under the influence of certain illegal drugs or prescription medications without a valid prescription, regardless of whether you were driving, causing a disturbance, or even in possession of the substance at the time.

A conviction under 11550 HS can result in up to a year in county jail, probation, mandatory drug counseling, community service, and a permanent criminal record that can affect employment, housing, and even professional licensing. For non-citizens, it may also trigger immigration consequences.

For many people, this charge comes after a sudden police encounter — a traffic stop, a call for service, or being in the wrong place at the wrong time. You may have been tested based solely on an officer’s observations or a questionable drug evaluation. It’s important to know that being charged does not mean you will be convicted. Prosecutors must prove beyond a reasonable doubt that you were actually under the influence, and there are many ways to challenge the evidence.

At The Law Offices of Arash Hashemi, our Los Angeles criminal defense attorney has over 20 years of experience defending clients against drug-related charges, including 11550 HS cases. We move quickly to examine the arrest, challenge unreliable testing methods, and push for alternatives to jail such as diversion programs or complete dismissal of charges. If you or someone you care about is facing an “under the influence” charge in Los Angeles County, contact our office today for a free, confidential consultation and immediate help protecting your future.

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    What Is Health & Safety Code § 11550 HSC?

    Being “under the influence” in this context means your physical or mental abilities are noticeably impaired by a controlled substance, whether it’s an illegal drug or certain prescription medication taken without a valid prescription. The law is broad — you can be charged even if you weren’t driving, causing a disturbance, or committing any other offense.

    Common substances that can lead to an HSC 11550 charge include:

    • Methamphetamine and other stimulants

    • Heroin, cocaine, or crack cocaine

    • LSD, psilocybin, or other hallucinogens

    • Prescription opioids or anti-anxiety medications without a prescription

    Prosecutors only need to show that you were willfully under the influence, which they can try to prove through officer observations, witness statements, or chemical test results. Because these cases often rely on subjective police reports or flawed testing, it’s critical to have a skilled Los Angeles criminal defense attorney review the evidence and challenge weak or unreliable proof.

    Examples of Conduct That Can Lead to a 11550 HS Charge

    An arrest for being under the influence of a controlled substance can happen in many different settings — not just in public or during a traffic stop. In fact, police often file these charges based on relatively small amounts of evidence if they believe your behavior or appearance suggests drug use. Common scenarios include:

    • Visible signs of impairment after drug use – Slurred speech, dilated pupils, unsteady movements, or erratic behavior observed by law enforcement.

    • Taking prescription medication without a prescription – For example, using someone else’s painkillers or sedatives and appearing visibly intoxicated.

    • Testing positive during a police investigation – Even if you weren’t the focus of the investigation, a positive chemical test for a controlled substance can lead to charges.

    • Found with other drug-related evidence – Being in possession of paraphernalia such as needles, burnt foil, or pipes while appearing impaired.

    • Private home incidents – Police responding to a disturbance or welfare check who believe you’re under the influence can still make an arrest, even if you were inside your own residence.

    Because the threshold for “under the influence” under 11550 HS can be low, it’s not uncommon for people to face charges based on minimal or questionable observations. That’s why early legal intervention can be key to avoiding a conviction.

    Penalties for Being Under the Influence of a Controlled Substance

    In most cases, a charge under Health & Safety Code 11550 is filed as a misdemeanor. While this is less severe than a felony, the consequences can still have a lasting impact on your life.

    Possible criminal penalties include:

    • Up to 1 year in county jail

    • Misdemeanor probation (often with strict terms)

    • Mandatory drug counseling or rehabilitation

    • Court fines and administrative fees

    Diversion and treatment options
    For many first-time offenders, California offers alternatives to jail, such as:

    • PC 1000 (Pretrial Diversion) – Allows you to complete a court-approved drug education program in exchange for having the charge dismissed.

    • Proposition 36 – A treatment-based sentencing option that focuses on recovery rather than incarceration.

    Collateral consequences
    Even if no jail time is imposed, a conviction can still lead to:

    • A permanent criminal record, which may affect employment, housing, and educational opportunities

    • Immigration consequences for non-citizens, including possible deportation or inadmissibility

    Related Drug Offenses

    Legal Defenses to 11550 HS Charges

    If you’ve been accused of being under the influence of a controlled substance under Health & Safety Code 11550, our Los Angeles criminal defense attorney can review the evidence and build a defense strategy specific to your case. Depending on the facts, we may be able to argue one or more of the following defenses:

    You were not actually under the influence
    Signs such as unsteady movement, dilated pupils, or slurred speech can be caused by many things other than drug use — including exhaustion, stress, or medical conditions. If the prosecution cannot prove impairment beyond a reasonable doubt, the charge should not stand.

    Flawed or unreliable drug testing
    Drug test results are only as reliable as the methods used to collect and analyze them. Contamination, mishandling of samples, improper storage, or inaccurate testing equipment can all lead to false positives. We carefully review lab protocols and chain-of-custody documentation.

    Valid prescription
    If the substance in question was legally prescribed to you and taken in accordance with your doctor’s instructions, you may have a complete defense. Lawful medical use is not the same as being unlawfully “under the influence.”

    Medical condition explanation
    Certain medical or neurological conditions — such as diabetes, seizures, or mental health disorders — can mimic the symptoms police associate with drug intoxication. Expert testimony and medical records can be powerful evidence in your defense.

    Illegal stop, detention, or search
    If police stopped you without reasonable suspicion or probable cause, or if they conducted a search in violation of your Fourth Amendment rights, any resulting evidence — including drug test results — may be excluded from trial. Without that evidence, the prosecution’s case may collapse.

    False accusation or mistaken identity
    Misunderstandings, personal disputes, or mistaken identification can lead to wrongful arrests. We work to uncover inconsistencies in witness accounts and prove you were not under the influence of illegal drugs.

    At The Law Offices of Arash Hashemi, we challenge every aspect of the prosecution’s case — from the initial police contact to the reliability of testing methods — to protect your rights and fight for the best possible outcome.

    Speak With a Los Angeles Drug Crimes Defense Attorney Today

    Attorney Arash Hashemi has over 20 years of experience representing clients charged with drug offenses, including allegations of being under the influence of a controlled substance. He knows how prosecutors approach these cases and understands the importance of challenging the evidence, questioning the accuracy of drug tests, and exposing constitutional violations that can lead to a dismissal.

    In many 11550 HS cases, jail is not the only option. Eligible individuals may be able to avoid a conviction through drug diversion programs, such as Proposition 36, Penal Code 1000 (deferred entry of judgment), or California drug court. These alternatives focus on treatment and rehabilitation rather than punishment — and we will fight to get you qualified if you are eligible.

    Our goal is to protect your freedom, your record, and your future. Contact our office today to schedule a free, confidential case review with our criminal defense attorney and learn how we can begin building your defense.

    The Law Offices of Arash Hashemi
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    Los Angeles, CA 90064
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    Arash Hashemi, a skilled Los Angeles criminal defense attorney, providing expert legal representation for clients in California.