Penal Code 1538.5 is the motion to suppress, the single most powerful tool in a DUI defense. It is how I ask the court to throw out evidence that was obtained through an unlawful stop, search, or seizure. I am Joel Brand, and here is how it works and why it can decide a case.
The text of the law
Penal Code 1538.5(a)(1). A defendant may move for the return of property or to suppress as evidence any tangible or intangible thing obtained as a result of a search or seizure on either of the following grounds: (A) The search or seizure without a warrant was unreasonable. (B) The search or seizure with a warrant was unreasonable because any of the following apply: ...
What the motion does
A motion to suppress under 1538.5 asks the court to exclude evidence that was obtained in violation of the Fourth Amendment's protection against unreasonable searches and seizures. In the DUI context, the most common ground is that the search or seizure happened without a warrant and was unreasonable, which the statute expressly covers in subparagraph (A). Because nearly every DUI begins with a warrantless traffic stop, this provision is the gateway to challenging the entire case.
Why the traffic stop is the key
A traffic stop is a seizure under the Fourth Amendment, and to be lawful it must be supported by at least a reasonable suspicion that a law was being violated. If the officer did not have a valid, articulable reason to pull you over, the stop was unlawful. And here is the crucial part: when the stop is unlawful, everything that flows from it, the officer's observations, the field sobriety tests, the statements, and the chemical test results, can be suppressed as fruit of that unlawful seizure. That is why a successful 1538.5 motion so often does not just weaken a DUI; it ends it.
Common grounds in a DUI
I look hard at several recurring issues. Was the stated reason for the stop, a weaving, a speed, an equipment violation, actually a violation at all, or does the video show ordinary driving? Was a DUI checkpoint operated according to the strict constitutional requirements, or was it defective? Was the detention prolonged beyond what the initial reason justified? Was a blood draw taken without a warrant or valid consent where one was required? Each of these can support a motion to suppress, and each can knock out the evidence the prosecution needs.
How the motion is litigated
A 1538.5 motion is litigated at a hearing where the prosecution must justify the search or seizure. For a warrantless stop, the burden is on the government to show it was reasonable. I typically call or cross-examine the officer, introduce the dash-cam and body-cam footage, and test the stated justification against what the evidence actually shows. The gap between the officer's written report and the recordings is frequently where the motion is won, because an account that sounded sufficient on paper often falls apart when measured against the video.
The consequences of winning
If the motion is granted, the suppressed evidence cannot be used against you. In a DUI, where the case is built almost entirely on what the officer observed and measured after the stop, suppressing that evidence usually leaves the prosecution with nothing to prove its case, and a dismissal commonly follows. Even a partial victory, suppressing some key piece of evidence, can dramatically weaken the prosecution and improve the resolution. This is why I treat the suppression analysis as a priority in every case.
Blood draws and warrants
Warrantless blood draws deserve special mention. The law generally requires a warrant for a blood draw unless a recognized exception applies, and the rules around consent and exigency are demanding. Where blood was drawn without a warrant and without valid consent, a 1538.5 motion can seek to suppress the blood result, which is often the cornerstone of the prosecution's chemical evidence. I examine exactly how any blood sample was obtained, because an improper draw can take the central evidence out of the case.
Timing and preserving the issue
A motion to suppress has to be brought properly and on time, and the statute sets out the procedure for raising it at different stages of the case. Failing to bring the motion can waive the issue, which is one reason having the search-and-seizure analysis done early matters so much. I assess every case for suppression issues from the outset and preserve and litigate them at the right time, so a winning argument is never lost to a procedural misstep.
It pairs with the rest of the defense
The motion to suppress works hand in hand with the other defenses. The same problems with the stop that support a suppression motion often also undermine the DMV's case at the administrative hearing, and challenges to the chemical testing reinforce both. I develop the suppression issues alongside the attacks on the field sobriety testing and the chemistry, so the case is challenged on every front at once.
Checkpoints and the special rules
DUI checkpoints deserve their own mention because they are a frequent source of suppression issues. A checkpoint is a seizure conducted without individualized suspicion, which the courts permit only if it satisfies a set of strict constitutional requirements: supervisory officials must make the key operational decisions, the criteria for stopping vehicles must be neutral, the location and timing must be reasonable, the checkpoint must be adequately marked and publicized, and motorists must be detained only briefly. When a checkpoint fails to meet these standards, the stop that came out of it is unlawful, and a motion to suppress can exclude everything that followed. I obtain the operational plans, the supervisory authorizations, and the publicity records for any checkpoint, because these technical requirements are often where a checkpoint case is won.
How it fits the larger defense
The motion to suppress under 1538.5 is the foundation of attacking the lawfulness of the stop, the most powerful category of DUI defense. It connects to the common police mistakes at a DUI stop and runs through nearly every statute in this section. See my top DUI defenses and the defenses guide.
Think your stop was unlawful? Let's talk.
Whether the stop and search hold up is exactly what I review against the video, and a motion to suppress can decide your case. Use the free case analysis on this page, or call me directly at (888) 271-6644. I answer my own phone, 24/7.
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