## 4th Amendment + suppression motions in Missouri The **4th Amendment** protects against unreasonable searches + seizures. Missouri criminal defendants can move to suppress evidence obtained illegally — and successful suppression often results in case dismissal when key evidence is excluded. ## 4th Amendment basics **Constitutional text:** "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause..." **Two key requirements:** - **Reasonable expectation of privacy** (Katz v. United States) - **Government action** (private searches not covered) ## When 4th Amendment applies **Search:** - Government intrusion into protected area - Reasonable expectation of privacy - Physical intrusion or technological intrusion **Seizure:** - Meaningful interference with possessory interests - Person, property, papers - Stops + arrests ## Warrant requirement **General rule:** - Warrants required for searches - Issued by neutral magistrate - Probable cause required - Particularity (place, things to seize) - Oath / affirmation **Exceptions to warrant requirement:** (Many — see below) ## Major warrant exceptions **1. Consent:** - Voluntary consent permits search - Must be free + voluntary - Authority to consent (apparent authority OK) - Can be limited in scope - Can be withdrawn - COMMON method police bypass warrant **2. Plain view:** - Officer lawfully present - Item obviously incriminating - Lawful right of access - No exploration **3. Exigent circumstances:** - Hot pursuit - Risk of destruction of evidence - Risk of escape - Risk of harm to others - Limited application **4. Search incident to arrest:** - Lawful arrest - Person + immediate area - Reasonable scope - Cell phones require warrant (Riley v. California 2014) **5. Automobile exception:** - Probable cause vehicle contains evidence - Mobile vehicles - Can search anywhere evidence might be - Including containers (Wyoming v. Houghton) **6. Inventory searches:** - Vehicle impounded - Standardized inventory procedures - Documenting belongings - Specific scope limits **7. Stop + frisk (Terry stops):** - Reasonable suspicion (lower than probable cause) - Limited weapon-pat-down - Must articulate facts - Limited scope + duration **8. Border searches:** - International borders - Reduced expectation of privacy - Some limits at international airports **9. Special needs:** - Specific purposes beyond law enforcement - DUI checkpoints - School searches - Specific limited circumstances **10. Open fields:** - No expectation of privacy in open fields - Distinguishes from curtilage - Even posted property ## The exclusionary rule **Mapp v. Ohio (1961):** - Evidence obtained illegally inadmissible - Applies to states (4th + 14th Amendments) - Deters police misconduct - Crucial enforcement mechanism **Fruit of the poisonous tree:** - Evidence derived from illegal evidence also excluded - Wong Sun v. United States (1963) - Subsequent searches / statements affected - Tree analogies **Exceptions to exclusionary rule:** - **Good faith** (Leon) - **Independent source** - **Inevitable discovery** - **Attenuation** ## Common search/seizure issues **Traffic stops:** - Reasonable suspicion / probable cause for stop - Reasonable extension (limited) - Pretext OK if proper basis (Whren) - Search of vehicle (PC required for full search) - Pat-down passengers (specific basis) - Drug-detection dogs (Rodriguez — limited extension) **Home searches:** - Strongest privacy expectation - Warrant generally required - Consent issues common - Knock-and-announce (Wilson v. Arkansas) - No-knock warrants (Hudson v. Michigan) - Curtilage protections **Stops + arrests:** - Reasonable suspicion for stop - Probable cause for arrest - Specific articulable facts - Officer's training + experience - Totality of circumstances **Cell phones / digital evidence:** - Warrant required for cell phone search incident to arrest (Riley) - Specific authorization for emails / data - Plain view limited in digital context - Encryption + passwords - Carpenter v. United States (cell-site location) **Drug-sniffing dogs:** - Around vehicles (Caballes — OK during stop) - At doors (Florida v. Jardines — search) - Cannot extend stop - Specific training + reliability ## Suppression motion process **1. Motion to suppress:** - Filed before trial - Specific allegations - Identified evidence - Legal grounds **2. Government response:** - Justify search/seizure - Specific exceptions claimed - Officer testimony **3. Suppression hearing:** - Defendant's testimony (limited) - Officer's testimony - Documentary evidence - Witnesses **4. Court ruling:** - Findings of fact - Conclusions of law - Specific evidence excluded / admitted - Reasons given **5. Trial proceeds with admissible evidence:** - If key evidence excluded, often dismissal - If evidence admitted, defendant goes to trial ## Standing **Defendant must have standing:** - Own privacy interest violated - Not just any constitutional violation - Cannot challenge searches of others - Specific to defendant ## Specific successful arguments **Common winning arguments:** **Vehicle stops:** - No reasonable suspicion for stop - Stop unreasonably extended - Search exceeded scope - Drug dog used improperly - Pat-down without basis **Home searches:** - Warrant lacked probable cause - Warrant overbroad / lacked particularity - Officers exceeded scope - Knock-and-announce violations (some states) - Curtilage violations - Consent involuntary - Consent exceeded scope **Cell phone evidence:** - Searched without warrant - Warrant scope exceeded - Specific apps not covered - Encryption issues **Statements + Miranda:** - No Miranda warnings - Custodial interrogation - Coerced statements - Right to attorney violated ## State constitutional protections **${s.name} state constitution may provide:** - Stronger protections than federal - Different exclusionary rule - Different consent rules - Different exceptions - Specific state precedents **Notable state constitutions** with stronger protections: - Washington - Oregon - New Jersey - California (sometimes) - Vermont ## Strategic considerations **For criminal defense:** **Always evaluate:** - Was stop legal? - Was extension reasonable? - Was search supported? - Was scope appropriate? - Were warrants valid? - Were exceptions properly applied? - Were warnings given? - Was consent voluntary? **Common winning patterns:** - Pretextual stops gone too long - Improper searches incident to arrest - Inadequate warrant affidavits - Drug-dog search extensions - Coerced consent - Cell phone searches - Curtilage violations ## Discovery in suppression cases **Critical discovery:** - Body-worn camera footage - Dashboard camera footage - Officer reports (specific + detailed) - Officer training + history - Specific dog certification + training - Specific search warrant + supporting affidavit - Inventory documentation - Communications + radio traffic ## Recent Supreme Court rulings **Notable cases:** - Carpenter v. United States (2018) — cell-site location - Caniglia v. Strom (2021) — community caretaker - Lange v. California (2021) — hot pursuit + minor offense - Vega v. Tekoh (2022) — Miranda + § 1983 - Always check current law ## What you should do If charged in Missouri based on potentially illegal search: hire criminal defense attorney with strong 4th Amendment experience. Suppression motions can dramatically change cases — sometimes leading to dismissal. Most Missouri criminal defense attorneys handle these motions. Specific facts matter — every search is unique. --- *This guide is general information about federal + Missouri constitutional law as of mid-2026 and is not legal advice. Search + seizure law is technical + fact-specific. Talk to a licensed Missouri criminal defense attorney about your specific case.*