Washington Marijuana and Drug DUI Lawyer

If you were arrested after using marijuana, prescription medication, or another drug, a Washington drug DUI lawyer can evaluate the blood evidence, police investigation, toxicology results, and potential driver’s-license consequences. Washington drug DUI cases can be more complicated than alcohol DUI cases because the presence of a drug does not necessarily answer whether a driver was impaired.

Washington law allows prosecutors to pursue DUI charges based on marijuana, prescription medication, other drugs, or combinations of substances. These cases may involve blood testing, prescription records, statements to police, field sobriety testing, Drug Recognition Expert evaluations, toxicology evidence, and separate Department of Licensing proceedings.

A person who lawfully used a prescription can still be accused of DUI. Likewise, a THC result below Washington’s 5.00 ng/mL threshold does not automatically require dismissal.

Understanding which legal theory the State is using—and what the evidence actually establishes—is an important part of evaluating a drug DUI case.

For a broader overview of impaired-driving law, see our guide to Washington DUI laws.

What Counts as a Drug DUI in Washington?

Washington’s primary DUI statute is RCW 46.61.502.

Under that statute, a person may commit DUI by driving in Washington:

With an alcohol concentration of 0.08 or more within two hours of driving;
With a THC concentration of 5.00 ng/mL or more within two hours of driving;
While under the influence of or affected by intoxicating liquor, cannabis, or any drug; or
While under the combined influence of alcohol, cannabis, and drugs.

This distinction is important because a Washington drug DUI does not always depend on a particular laboratory number.

For marijuana, the State may pursue a numeric per se theory based on a qualifying THC concentration. It may also attempt to prove actual impairment based on the total evidence.

For prescription medication and most other drugs, there generally is not a universal numeric concentration that automatically establishes DUI under RCW 46.61.502.

Most DUI offenses are gross misdemeanors, although certain criminal histories can elevate an impaired-driving offense to a felony.

For more information about potential sentencing consequences, see our guide to Washington DUI penalties.

Washington Drug DUI Lawyer: Marijuana Versus Other Drug Charges

Drug DUI cases can look very different depending on the substance involved.

Issue	Cannabis	Prescription or Other Drugs
Numeric per se DUI rule	5.00 ng/mL THC within two hours	Generally no universal numeric per se limit
Impairment theory	Available even below 5.00	Available based on the total evidence
Common chemical evidence	Blood testing	Blood testing
Lawful possession/use	No automatic defense	No automatic defense
Key evidentiary issues	THC level, timing, observations, toxicology	Substance, dosage, timing, observations, toxicology

The important point is that detection and impairment are not necessarily the same question.

A drug may be present in a person’s blood, but the prosecution must still prove the elements of the particular DUI theory being charged.

Can You Get a DUI for Prescription Medication in Washington?

Yes.

Washington law specifically provides that a person’s legal entitlement to use a drug does not, by itself, constitute a defense to DUI. See RCW 46.61.502(2).

That means someone who took medication exactly as prescribed can still be investigated or charged with DUI.

But lawful prescription use also does not automatically prove impairment.

Evidence in a prescription-drug DUI case may include:

The medication allegedly taken;
Dosage and timing;
Prescription and pharmacy records;
Driving observations;
Statements attributed to the driver;
Field sobriety test performance;
Drug Recognition Expert observations;
Blood-test results;
Alcohol use; and
Other medications or substances.

Cases may involve sleep medications, pain medications, anxiety medications, stimulants, or other drugs.

An attorney examining the case may look at whether the evidence establishes that the drug actually affected the defendant’s ability to drive, rather than simply showing that the substance was present.

How Washington Investigates Suspected Drug DUI Cases

A suspected drug DUI investigation may begin with a traffic stop, unusual driving, a collision, or another police contact.

The investigation may include several stages.

Driving Observations

An officer may report weaving, speeding, unusually slow driving, delayed reactions, a collision, or some other driving behavior.

Those observations may later become part of the State’s impairment theory.

Questions About Marijuana or Medication

Officers may ask whether a driver has consumed marijuana, medication, alcohol, or another substance.

Statements made during the investigation can become evidence.

Anyone facing a DUI investigation should understand that their own statements can affect the case.

For additional information about roadside investigations, see what to do when pulled over for DUI in Washington.

Field Sobriety Tests

Police may ask a driver to perform standardized or other roadside exercises.

The significance of those observations depends on the facts of the case.

Drug Recognition Expert Evaluation

A Drug Recognition Expert, often called a DRE, is a law-enforcement officer trained to conduct a structured evaluation intended to identify signs associated with categories of drugs.

A DRE evaluation can involve observations, physical measurements, questioning, and other investigative steps.

The officer’s training, observations, report, conclusions, and adherence to applicable procedures may become important evidence in a drug DUI case.

Is Washington’s Roadside Oral-Fluid Drug Test Voluntary?

Yes.

Washington enacted RCW 46.61.5062, which governs roadside oral-fluid testing used by law-enforcement agencies.

The statute requires an officer administering such a test to advise the driver that:

The test is voluntary;
It does not satisfy Washington’s implied-consent requirements;
The results may not be used against the person in court; and
Taking the oral-fluid test is not an alternative to an evidentiary breath or blood test.

A roadside oral-fluid test should therefore not be confused with an evidentiary blood test.

It is investigative information subject to its own statutory limitations.

Blood Tests in Washington Drug DUI Cases

Blood evidence is often central to marijuana and other drug DUI investigations.

Washington’s chemical-testing statute, RCW 46.61.506, regulates numerous aspects of DUI chemical evidence.

A blood-test case can involve several distinct questions.

Was a Substance Detected?

The laboratory may report that a particular substance or metabolite was found.

Detection alone does not necessarily answer whether the substance impaired the person at the time of driving.

What Concentration Was Reported?

Some substances may be quantified.

For THC, Washington’s DUI statute gives particular legal significance to a concentration of 5.00 ng/mL or more within two hours of driving.

Other drugs generally do not have the same universal statutory cutoff.

When Was the Blood Collected?

Timing can be important.

The interval between alleged driving, drug use, arrest, and blood collection may be relevant to how the evidence is interpreted.

How Was the Sample Collected and Tested?

Issues may include:

Who performed the blood draw;
Whether the draw was legally authorized;
Collection procedures;
Sample preservation;
Documentation;
Chain of custody;
Laboratory methodology;
Testing records; and
Quality-control information.

RCW 46.61.506 also provides that a person tested may obtain additional testing from a qualified person and may request full information concerning tests performed at law enforcement’s direction.

The Washington State Patrol also publishes its DUI/DRE toxicology testing scope. Laboratory protocols can change, so current official materials should be consulted instead of assuming that historical procedures remain in effect.

What If My THC Result Is Below 5.00?

A THC result below 5.00 ng/mL does not automatically dismiss a Washington marijuana DUI case.

This is one of the most important distinctions in Washington cannabis DUI law.

Under RCW 46.61.506, a THC concentration below 5.00 may still be considered with other competent evidence when determining whether the driver was under the influence.

In practical terms:

A result below 5.00 does not satisfy the statutory 5.00-or-higher per se theory.
The prosecution may still pursue an actual-impairment theory.
Other evidence may include driving behavior, statements, field tests, DRE observations, and other circumstances.
The defense may examine whether the complete evidence reliably establishes impairment.

So a result of 4.00, 3.00, or another amount below 5.00 should not be treated as an automatic conviction or an automatic dismissal.

The legal significance depends on the prosecution’s theory and the rest of the evidence.

Can a Drug DUI Affect Your Washington Driver’s License?

Yes, but it is important to separate the criminal case from the Department of Licensing proceeding.

These are two different processes.

The Criminal DUI Case

The criminal case is handled through the court system and determines issues such as guilt, sentencing, court conditions, fines, and other criminal consequences.

The Department of Licensing Case

Washington’s implied-consent statute, RCW 46.20.308, authorizes DOL action under specified circumstances involving test refusal and qualifying alcohol or THC results.

For a driver age 21 or older, the statute identifies a THC concentration of 5.00 ng/mL or more as one basis for administrative action.

A positive result for some other drug should not automatically be described as producing the same administrative suspension. The statutory basis for DOL action must be examined.

The DOL Hearing Deadline Is Short

A person receiving the applicable DOL notice generally has seven days after notice is given to request a formal hearing.

That deadline is extremely important.

Missing the deadline can affect the ability to challenge the administrative license action.

The DOL proceeding can also move separately from the criminal case, meaning a person may have to address both at approximately the same time.

Drug DUI Blood Results May Arrive Long After the Arrest

One feature of many Washington drug DUI cases is delay.

Unlike a typical breath-test alcohol DUI, a blood sample generally must be analyzed by a laboratory. That can mean the investigation remains open while toxicology testing is completed.

A person may therefore be released after arrest and later receive a summons or charging documents.

The absence of immediate charges does not necessarily mean the case has ended.

Anyone who receives later court papers should carefully review the appearance date and respond appropriately.

Possible Consequences of a Washington Drug DUI

A drug DUI conviction may carry significant consequences.

Depending on the person’s prior history, the evidence, and the charge, consequences may include:

Jail or alternative confinement;
Fines and assessments;
Driver’s-license suspension or revocation;
Ignition-interlock requirements;
Substance-use evaluation;
Treatment requirements;
Probation or other court supervision;
Release conditions;
Increased insurance consequences; and
Potential employment, professional licensing, military, or immigration concerns.

Washington DUI sentencing can become complicated, particularly when prior impaired-driving offenses are involved.

For a detailed overview, see Washington DUI mandatory minimum penalties.

How a Washington Drug DUI Lawyer May Examine the Evidence

There is no single defense that applies to every drug DUI case.

Instead, an attorney may investigate multiple legal and evidentiary issues.

The Traffic Stop or Initial Police Contact

Was there a lawful basis for stopping or detaining the driver?

The Arrest

Did the facts establish the legal basis required for the arrest?

The Blood Draw

Was the blood sample obtained under legally authorized circumstances?

Depending on the case, issues may involve a warrant, consent, exigent circumstances, or other lawful authority.

Blood Collection and Chain of Custody

An attorney may review how the sample was collected, labeled, stored, transported, and documented.

Laboratory Testing

The underlying laboratory records may matter—not just the final reported number.

Toxicology Interpretation

The defense may examine what the laboratory evidence does and does not establish about the driver’s condition at the time of driving.

DRE Evidence

A DRE officer’s training, methodology, observations, documentation, and conclusions may be reviewed.

Other Explanations for Observed Behavior

Fatigue, illness, injury, nervousness, environmental conditions, or other facts may sometimes provide alternative explanations for observations attributed to impairment.

Whether such an explanation is supported depends on the actual evidence.

Statements

Statements attributed to the defendant may become important.

Body-camera footage, patrol-car video, reports, and recordings can sometimes clarify what was actually said and the circumstances surrounding it.

No single issue automatically guarantees dismissal or reduction. Drug DUI cases require individualized evaluation.

Drug DUI Versus Physical Control in Washington

Not every impaired-driving allegation involves a vehicle actually being driven at the moment police arrive.

Washington also has an offense known as physical control.

A person may face a physical-control allegation when accused of being under the influence while in actual physical control of a vehicle even though the vehicle was not necessarily moving.

For more information, see our guide to Washington physical control DUI.

Drug DUI Cases in Washington Local Courts

Misdemeanor DUI cases are typically handled in the court with jurisdiction over the location of the alleged offense.

Blanford Law handles matters in Washington jurisdictions that may include King County, Pierce County, Kitsap County, Tacoma, Seattle, and Upper Kittitas.

Local procedure can differ even though the underlying Washington DUI statute is statewide.

Court-specific considerations may include:

Arraignment procedure;
Pretrial hearing schedules;
Filing practices;
Local rules;
Treatment or evaluation requirements;
Prosecutorial practices; and
How court appearances are conducted.

For example, defendants with matters in Cle Elum or surrounding areas can review our Upper Kittitas District Court guide.

The statewide drug DUI guide should serve as the substantive legal hub, while local court pages explain court-specific procedure.

What Should You Do After a Drug DUI Arrest?

If you have been arrested or are waiting for blood-test results, several practical steps may help preserve important information.

Read Every Notice Carefully

Review paperwork from law enforcement, the court, and the Department of Licensing.

Calendar the DOL Deadline Immediately

If you receive a qualifying DOL notice, the hearing-request deadline may be only seven days.

Do not assume the criminal court will protect your DOL rights automatically.

Preserve Prescription Information

Keep relevant prescription bottles, pharmacy records, medication instructions, and related documentation.

Do not alter records or manufacture documentation after the fact.

Save Court and Police Paperwork

Keep citations, property sheets, warrants, notices, hospital paperwork, and other documents together.

Do Not Miss a Summons or Arraignment

Blood-test cases can result in charges being filed weeks or months after the original investigation.

Avoid Discussing the Facts Publicly

Public posts and messages can create unnecessary evidentiary problems in a pending criminal case.

Speak With a Washington DUI Attorney

A lawyer can evaluate the criminal case, toxicology evidence, and any DOL proceeding.

How Blanford Law Helps With Marijuana and Drug DUI Cases

Drug DUI cases can require careful review of more than a police report.

Depending on the circumstances, representation may involve examining:

Police reports;
Body-camera footage;
Court filings;
Search warrants;
Blood-draw records;
Toxicology reports;
Laboratory documentation;
Prescription records;
DRE evidence;
Department of Licensing issues; and
The circumstances leading to the traffic stop and arrest.

Blanford Law represents clients facing criminal matters in Washington and can review the evidence and procedures involved in an individual case.

No attorney can responsibly guarantee that a drug DUI charge will be reduced or dismissed. Outcomes depend on the law, evidence, criminal history, prosecutorial decisions, and the individual circumstances of the case.

Frequently Asked Questions About Washington Drug DUI Charges

Can I get a DUI in Washington for prescribed medication?

Yes. Washington law provides that lawful entitlement to use a drug does not automatically prevent a DUI charge. However, the State must still prove the required elements of DUI.

Is a THC level below 5.00 still a DUI?

It can be. A THC concentration below 5.00 does not establish the statutory 5.00-or-higher per se theory, but Washington law allows the result to be considered with other competent evidence on the question of impairment.

Is Washington’s roadside oral-fluid test voluntary?

Yes. RCW 46.61.5062 states that roadside oral-fluid testing is voluntary. It also does not replace an evidentiary breath or blood test.

Can police require a blood test after a drug DUI arrest?

Whether a blood draw is lawful depends on the circumstances and the legal authority supporting it. Issues can include a search warrant, consent, exigent circumstances, or another recognized legal basis.

How long do Washington drug DUI blood results take?

Timing varies. Blood samples generally require laboratory analysis, and processing times can change based on laboratory workload and testing needs. A specific turnaround time should not be assumed.

Does any positive drug test automatically suspend my Washington driver’s license?

No. DOL action depends on the statutory basis for administrative action. A positive test for a drug other than alcohol or a qualifying THC result should not automatically be treated as triggering the same implied-consent suspension.

Can marijuana DUI charges be reduced or dismissed?

They can sometimes be reduced or dismissed, but no result is automatic. Outcomes depend on the evidence, legal issues, case history, negotiations, and court proceedings.

What is a Drug Recognition Expert?

A Drug Recognition Expert is a law-enforcement officer who has received specialized training to conduct structured evaluations of drivers suspected of drug impairment.

Are drug DUI penalties different from alcohol DUI penalties?

Both fall under Washington’s impaired-driving laws, but the evidentiary issues can be very different. Sentencing depends on the applicable statutes, prior history, and circumstances.

Which court will handle my Washington drug DUI case?

Jurisdiction generally depends on where the alleged offense occurred and whether the charge is a misdemeanor or felony. A misdemeanor case may proceed in district or municipal court.

Contact a Washington Drug DUI Lawyer

Drug DUI cases can involve criminal charges, blood evidence, toxicology interpretation, prescription records, and separate driver’s-license deadlines.

Getting those issues reviewed early can help ensure that important deadlines and evidence are not overlooked.

Contact Blanford Law today at ken@blanfordlaw.com or 253-720-9304 for guidance on your legal matter.