How to Challenge an Illegal Traffic Stop. Motion to Suppress Explained, Recommended Form.

Illegal Stop? Challenge it!

No matter what state you live in, Federal Law controls whether or not a stop of a vehicle by police is legal. If the police stop a vehicle illegally, the evidence directly obtained from that illegal action cannot be used in court as admissible evidence.

Moreover, no matter what state a criminal or traffic ticket case is in, all criminal and traffic court defendants can challenge the legality of a vehicle stop separately from any other defense they may have. They should not fell bad about doing it either, because it is their Constitutional Right.

Here is how it works, and we have even made a Motion to Suppress Self Help Form for you to use in your own case.

4th Amendment Background

All Warrantless Searches and Seizures are “per se” Unreasonable under the 4th Amendment to the US Constitution, and therefore presumed unlawful. The government has the burden to prove a seizure or search was legal.(4)

Of course there are exceptions to this constitutional warrant requirement. Police are allowed to stop a vehicle without a warrant if they witness the car involved in a crime.

But the police are not allowed to pull people over for no reason. They are not allowed to pull vehicles over solely because they have a “suspicion” something is wrong. They cannot pull over a vehicle just to see if the unknown driver has a valid drivers license.

Why? Because there is no way for the Officer to Reasonably suspect a crime has taken place, or that the driver did it. The driver is presumed innocent in America, and per the Fourth Amendment, all warrant-less searches and seizures are presumed illegal.

Of course there are exceptions to that blanket rule.

But the police cannot just pull someone over, “detain” them, because they “think” that the person is a gang member. American Police are not allowed to stop a vehicle just because they think the driver is a criminal, or illegal immigrant.

Naturally, sometimes, the police arrest or pull people over illegally anyway. And sometimes, after an illegal arrest or detention, the police discover evidence of a crime they were previously unaware of. Surprise! “I found evidence!”. If that post stop “discovered” evidence becomes the basis for a criminal prosecution, the defendant should challenge the stop with a Motion to Suppress.

One of the foundational pillars of criminal defense work is this “Motion to Suppress” or “Suppression Motion”. Defense Attorneys use them to not only to get evidence excluded, but also to get evidence out in the open prior to trial.

If a Motion to Suppress is won by a defendant, the ruling usually leads to the exclusion of some or all of the prosecution’s evidence. It can mean the exclusion of Blood Alcohol Test Results, or the status of a person’s drivers license, or of the gun in the back seat. Thus, a successful Motion to Suppress can cause the death of a criminal prosecution.

When is a Vehicle Stop Illegal?

A vehicle stop is a “Detention” within the meaning of the 4th Amendment to the US Constitution. All warrantless Detentions are per se illegal under the 4th Amendment.

A Detention starts: “whenever a police officer accosts an individual and restrains his freedom to walk away,” or when an officer stops an individual because he suspects that person “may be personally involved in some criminal activity.”(1)

Generally, this means a detention of a driver occurs at the moment the driver realizes the police officer has their lights flashing and that they are no longer free to drive where they want.

In order to justify a warrantless detention “the circumstances known or apparent to the officer must include specific and articulable facts causing him to suspect that (a) some activity relating to crime has taken place or is occurring or about to occur, and (b) the person he intends to stop or detain is involved in that activity. (2)

Not only must the officer subjectively entertain such a suspicion, but it must be objectively reasonable for him to do so: the facts must be such as would cause any reasonable police officer in a like position, drawing when appropriate on his training and experience, to suspect the same criminal activity and same involvement by the person in question.”(3)

The prosecution in a case – whether it be the police officer in traffic court or an Assistant District Attorney in a DUI case – has the legal burden to prove the Detention and Arrest were legal. The Defendant does not need to do anything but raise the issues and ask for a ruling from the judge.

If the judge denies the motion, a Defendant may appeal the denial in State Court, and if really ambitious, in Federal Court as well.

What Happens If a Stop is Ruled Illegal in Court?

The Defendant should argue that all evidence resulting from an illegal stop should be suppressed, which means excluded – thrown out – ignored. This includes officer’s observations about your drivers license, your own statements, your expired insurance card, should not be admitted as evidence.

How Does a Defendant Challenge an Illegal Stop?

The Detention or arrest can be challenged in any criminal or traffic court case. The challenge in made in open court, by making a “Motion” – or request to the Judge for a ruling on the subject. It can be made orally or in writing prior to trial.

The process will vary slightly from court to court. In California, Penal Code section 1538.5 controls the process.

In a misdemeanor case, such as a DUI, a CA “PC 1538.5 Motion”, as it is called by Criminal Defense Attorneys, is made by asking the judge at the Arraignment for a “1538.5″ hearing date. The judge normally will give a date and deadline for filing papers with the court clerk and prosecutor.

In some courts, the Motion must be filed with the court clerk first, and the court clerk chooses the date for the hearing.

Some judges, in some cases, will require a suppression motion hearing to take place the day before trial, or the morning before trial in a typical criminal case.

Can You Make the Motion to Suppress Yourself in a Traffic Ticket Case? Yes!

In a traffic court infraction case, it is unlikely that the court will give you a separate hearing date. So you will have to make the motion at the very start of a court trial.

When your case is called, simply tell the judge: “Your honor, I would like to make a pretrial motion to suppress under penal code section 1538.5. The stop was illegal. It is the government’s burden to prove it was legal. I ask for hearing and ruling on that issue prior to trial.”

A defendant can testify at a hearing on a Motion to Suppress if they choose, but it is almost never a good idea.

It is best to make it in writing, and to get a ruling on the record in court. Usually this means drafting the Motion (including a notice of motion) and filing it with the court clerk at least 10 court dates in advance of the date you want the judge to consider it.

In most courts, you can file a motion to suppress in court by telling the judge you have a motion to file, and by handing it to the courtroom clerk.

Extra copies should be made and have to be delivered to the prosecutor, or in traffic court the police officer who is testifying. Everyone involved must have notice of your motion and a copy.

Check your court’s local rules on criminal or traffic court filings to be sure the clerk does not give you a hard time.


For purposes of a Motion to Suppress Evidence Following Illegal Stop, you want the Detention to begin as soon as possible, because the sooner the detention starts, the less information the officer will have available to justify the stop.

A Motion to Suppress is a very good defense option to a traffic citation where the citation only lists a “proof of insurance” violation and does not list a reason for the stop. Or use it in cases where the citation on list a drivers license violation, like driving without a valid drivers license under Vehicle Code 12500(a). In such cases, it should be argued that whatever the reason given for the stop in court, it was made up, invented.

A detention can begin as soon as the officer turns on his/her patrol lights on behind a vehicle, or as soon as the driver believes he/she is not longer free to drive wherever they want.

At the moment the detention begins, the officer must have the required elements for a legal detention. What happens after the detention is irrelevant to the question of whether or not the detention is legal to start with.

Finally, when making a final argument on a Motion to Suppress, it is usually best to start out with: “Your honor, the government did not meet its burden to prove that the stop was legal . . . ”

If you lose a Motion to Suppress, you can file an Appeal after the hearing or after the case is over. There is no harm in doing the Motion and losing, and because it preserves issues for appeal, many attorney will “run the Motion” as a matter of course on nearly all cases.

Questions? Leave a Comment. We try to answer them all.


CA Motion to Suppress Evidence from Illegal Vehicle Stop (Penal Code 1538.5)


1. In re Tony C., 21 Cal. 3d 888 at p. 895; Terry v. Ohio, 392 U.S. 1, at p. 16;
2. People v. Superior Court (Kiefer), 3 Cal. 3d at p. 827, In re Tony C. 21 Cal. 3d 888 at p. 893; People v. Loewen (1983) 35 Cal. 3d 117, 123;
3. Id.
4. People v. Martino, (1985) 166 Cal.App.3d 777; People v. Williams (1988) 45 Cal.3d 1268.

About Attorney Christopher Dort

Public Interest Attorney. CA State Bar #196832. Licensed to practice law in California 1998, and then the US Federal District Court in 2000. Civil Litigation Trial Attorney (Insurance Defense Firms) 2000-2003. Private practice 2003 - present. First Solo Criminal Jury Trial 1998 (Santa Cruz County). First Civil Jury Trial 2002 (Orange County). Santa Cruz County Public Defenders Office 1996-1999 (law clerk). BA in Politics from UC Santa Cruz, 1995. JD, University of California, Hastings, 1998.
This entry was posted in California Legal Help, Defense Attorney Tactics, Going to Court, Traffic Court Forms. Bookmark the permalink.

12 Responses to How to Challenge an Illegal Traffic Stop. Motion to Suppress Explained, Recommended Form.

  1. Joseph A. says:

    I forgot to add that I was arrested for dui after the false 911 call.

  2. Joseph A. says:

    I was not in my car when the police arrived but they claim I was after the were called with a false and malicious 911 call that I was trying to break into someone’s apartment. Would a motion to suppress be a good ideal? would it be a legal stop if you can prove the 911 call was fake?

  3. Omar says:

    I was recently arrested for DUI. I was pulled over by one officer, in his own patrol car, but arrested by a different officer and his partner that were in another car. During the arrest process I asked one of the two arresting officers why in deed I had been pulled over. The officer stated that a good samaritan had phoned me in as a suspected DUI because I was driving to slow. I later requested a DMV hearing and obtained the arrest report. The arresting officer’s report states that the caller had followed me for about 5 miles on the highway updating the dispatcher on my location. The caller stated that I had reached speeds of 100 mph and that after almost colliding with him slowed to 40 mph, (which is not true). I was pulled over just outside town, passing the last on ramp to the highway. The report states that I was pulled over by the one officer that was on his own, then the arresting officer reports he arrived “20 seconds” later. There is no reason given on the report of why I was pulled over other than the good samaritan that called. Should I file a Motion to Supress based on that the stop was illegal? Thanks,

    • Omar,

      I think it is a good idea to challenge the stop in almost every DUI case for many, many reasons.

      Even if a suppression motion is denied, you still get the officer’s testimony locked into a transcript, for use later at trial, for example.

      You might have the right kind of facts to win on that issue here. Depends on what the witnesses say at the hearing.

      And of course, you have to expect and prepare for the possibility that the officers will have a totally different story once you get to court. One of them might realize they actually saw you swerve 7 inches to the right once they caught up to you.

      Not in the report? “Officer … isnt it true that you are trained to put all important things into your incident reports because you are told that they may be used as evidence in court?” . .. . .

      Can you do it alone, in your own case? Probably not. I would not recommend it. But if you want to try, there is no legal reason why you cannot. And you can use my template form to make your motion.

      The written part of most suppression motions form the Defendant is very short, and without much detail. Just an allegation that the stop was illegal. Why?

      It’s the government’s burden to prove the stop was legal, and because you really have no idea how the government may try to justify the stop in court. You need to be flexible.

      Suppression motions are won or lost in the hearing testimony and argument afterwards. The written motion is used to just get the challenge underway.

    • Omar says:

      Thank you Mr. Dort. Do you practice in the Northern California area or is there someone you can recommend? My initial court hearing is on July 22. Thank you.

  4. christopher says:

    Hello i was on the highway and a cop passes me by so i drive about a mile more ddown the highway pulled up ln to private property down dirt road obout a block long so i park my car got out and was talking to a friend and the next thing i know cop passes bye and turns around drives down drive way parks right next to my car and then he turns on his lightsand tells me to put my hand on the hood i asked him what was i doing wrong he stated i had no licence to drive from prior him stoping me two years ago for not having one so is this a illegal stop .

  5. JP says:

    My case is a stop for a right turn from the lane beside the right turn lane. The stop resulted in the addition of a no proof of insurance violation.

    Do I stand a chance using the above method to claim:

    Your Honor, there was a shopping cart in the right turn lane, so I had to turn right from the next lane. Officer Miller couldn’t see the shopping cart because he was in left turn lane [from which he made an extremely dangerous right turn to come and ruin my day] when he observed what he perceived to be an illegal maneuver. Therefore the stop was illegal and invalidates the resulting citations.

    • If a Police Officer Makes a Good Faith Error and Stops an Innocent Person, Is It an Illegal Stop?


      Ha! Great question.

      If the officer had a good faith belief, based upon specific and articulable facts, that you violated the vehicle code and he saw the violation (she?) – then it is a legal stop even if the officer was wrong.

      So on these facts, I’d say you might be completely innocent of the first count (alleged illegal turn), but it’s not an unconstitutional or illegal stop.

      If the stop is legal, the officer’s testimony about your lack of proof of insurance is admissible.

      But . . . had the officer stopped (detained you) based upon a different motivation – for example he just wanted to see if you had insurance – then you have an illegal stop and the evidence obtained from the stop must be excluded from any trial on the charges.

      Bottom line: a good faith error by an officer in a traffic stop does not make the entire stop illegal.

      Now, lets say the officer pulled you over because your registration tag was faded, and it looked expired at first to the officer. But then as the officer walks up to your car and sees that the sticker is in fact valid, just faded, the detention must end immediately. In my defense attorney opinion.

      The remedy for challenging an Illegal stop is a pre trial motion to suppress under authority of (in ca) Penal Code section 1538.5. To make the motion, just write up a short simple challenge, and get it filed with the court prior to trial. Serve the officer in advance with a copy of the motion.

      The government has the burden to prove the stop was legal. Because there is no warrant in a standard traffic stop – they are presumed illegal by the law. You are also presumed innocent.

      More Info: How to Challenge an Illegal Stop (and recommended self help form).

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  6. Nice move, counselor! Hopefully Molly will notice the subtlety and appreciate the value of a good litigator who knows “how” to ask questions.

  7. Molly says:

    Is this a good line of first defense for all traffic stops which ends up in traffic court? Ex. a cop pulls you over and asks to do all sorts of DUI things when in fact you haven’t been drinking at all. Then when they can’t find anything to prove that they site you for speeding which again is not legit. Can this defense be used to call the stop illegal because the cop first did the DUI tests and when that didn’t prove fruitful for them they made up another violation. thanks

    • Molly,

      That is really an advanced question. Hard to answer. The Motion is a good first line of defense even if you lose, always, every time.

      In your scenario, it would work like this:

      Defendant files motions
      Hearing comes, cop testifies that he saw defendant speeding.
      Cop shuts up;
      Defendant starts talking about DUI tests;
      Judge says: “Shut Up! The Stop was legal. He saw a violation.”

      But the savy attorney would approach it this way:

      You were on patrol;
      In a marked patrol car
      You were parked
      Where were you parked exactly?
      In the bushes by the side of the road where people stop to smoke out and pee.
      You were watching for something specific
      You were looking for drunk drivers or drivers driving unsafely?
      You contacted many drivers that day
      You asked many of them if they were drinking
      Most of them were not drinking
      Were they drinking?
      Most of them?
      Most of them were sober?
      You did not arrest all of them
      Did you arrest all of them?
      The drivers?
      Did all of them commit crimes?
      You let some people go?
      You arrested some people that day, or thought that you might?
      Yes, I arrest people
      You were looking for drunk drivers?
      Was defendant drunk?
      Did you arrest defendant?
      Did he tell you he was drunk?
      Did you arrest him?
      Were you hoping he was under the influence?
      Of course not
      Did you want to arrest him?
      He wasnt Speeding was he?

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