Miranda
Custody plus interrogation triggers the warnings requirement. Defective warnings, premature questioning, or invalid waiver puts the entire statement at risk.
Voluntariness
Even with proper Miranda, a statement obtained by physical, psychological, or coercive pressure can be suppressed as involuntary under the Due Process Clause.
Custodial Interrogation
The custody analysis turns on whether a reasonable person would feel free to leave. Misjudging custody is one of the most common pre-Miranda errors.
Franks & Warrant Defects
False statements or reckless omissions in a warrant affidavit can void the warrant and suppress all evidence. The defect is in the document, not the search.
Scope & Particularity
A warrant must describe with particularity what is to be seized. Overbroad warrants and overbroad executions both result in suppression.
Search Incident to Arrest
The exception is narrower than most officers think. A lawful arrest does not authorize an unbounded search of the arrestee's effects or vehicle.
Digital & Cell-Site Search
Phones, cell-site location, cloud data, and digital evidence require warrants under modern Fourth Amendment doctrine. Search-incident exceptions do not apply.
Two-Step Interrogation
Deliberately questioning without Miranda first to elicit an unwarned statement, then giving warnings and re-asking, produces suppression of both rounds.
Geofence & Keyword Warrants
Warrants that start with a whole population, every device in an area, or everyone who searched a term, and work backward to a suspect. Courts are split on whether they are unconstitutional general warrants, and the Supreme Court is deciding the question now.
Curtilage & the Home
The protected area immediately around a home, porch, driveway enclosure, yard, carries near-full Fourth Amendment protection. Stepping onto curtilage to investigate, including a dog sniff, can itself be a search.
Vehicle & Automobile Exception
Probable cause lets you search a vehicle without a warrant, but the exception does not let you enter a home's curtilage to reach a car, and it is narrower than the search-incident-to-arrest rule officers often confuse it with.
Exigent Circumstances
A true emergency, imminent escape, destruction of evidence, or danger to life, can justify a warrantless entry. Hot pursuit of a misdemeanant and community caretaking do not automatically qualify, especially at the home.
DUI & Chemical Testing
Breath tests are generally allowed incident to a DUI arrest; blood tests usually need a warrant. The natural dissipation of alcohol is not, by itself, an emergency that excuses the warrant.
Consent Search
Consent must be voluntary under the totality of the circumstances, and a present, objecting co-occupant can defeat it. Misrepresented authority or a pretextual removal of the objector invalidates the search.
Stop & Frisk
An investigative stop needs specific, articulable reasonable suspicion, and a frisk needs a separate basis to believe the person is armed. A stop cannot be prolonged for an unrelated investigation without new suspicion.
Exclusionary Rule
Evidence obtained in violation of the Fourth Amendment, and evidence derived from it, is generally suppressed. Good-faith reliance, attenuation, independent source, and inevitable discovery are the main ways evidence still comes in.
