Copyright 2001 - 2018  Edward S. Armstrong, Jr.

All law enforcement officers must confer with their training officers, legal advisors and prosecutors regarding the following legal issues. State law can be more restrictive (pro-defendant) than Federal law. Federal circuit courts of appeal often disagree with other Federal circuit courts on issues not yet decided by the United States Supreme Court. Also, lower courts (State and Federal) sometime disagree on what a Supreme Court decision means. The following statements are not to be taken as legal advice.

Back To Index Page

16.   PLAIN SIGHT, SOUND, SMELL – If Police are lawfully at a certain location, anything seen in plain view, heard, or smelled is legally seen, heard or smelled under the 4th Amendment.

LEGAL SEIZURE - However, to legally make a 4th Amendment seizure (of a person or physical evidence), Police must have reasonable suspicion to detain, probable cause to arrest, PC for plain view seizure, PC for exigency, a Search Warrant or Consent.

Taylor v. U.S., 52 S.Ct. 466 (1932)(Police located outside, saw contraband inside a garage. Police entered and seized the contraband. Illegal. Police needed a Warrant or Consent.

 U.S. v. Ventresca, 85 S.Ct. 741(1965)(Police saw criminal activity and smelled fermented mash coming from a suspect’s premises. Police entered with a SW and legally seized the contraband).

PLAIN TOUCH – If Police intend to touch a non-arrested or non-Terry stopped person’s opaque container and manipulate it to feel its contents, Consent or a Search Warrant is first required, Bond v. U.S., 120 S.Ct. 1462 (2000).

17.   KNOCK & TALK - 4th Amendment – Police may ask Consent from a suspect to enter the suspect’s premises and talk with the suspect.

 If the suspect consents, Police may enter without a warrant. If the suspect denies entry to his premises, Police may not enter without a Search Warrant.

U.S. v. Cephas, 254 F.3d 488 (4th Cir 2001), U.S. Jones, 239 F.3d 716 (5th Cir 2001), U.S. v. Cormier, 220 F.3d 1103 (9th Cir 2000), U.S. v. Tobin, 923 F.2d 1506 (11th Cir. 1991)(en banc).

a.   Knock & Talk at apartment door, then exigent circumstances not caused by Police, entry without Warrant or Consent is lawful, Kentucky v. King (2011)

b.   Knock & Talk at residence front porch with canine to smell odors for PC, not lawful without first obtaining Consent or a Warrant, Florida v. Jardines (2013)

c.   Knock & Talk - if a physically present co-inhabitant of a residence, (husband suspect), does not give consent for Police to enter, Police may not enter under the Consent theory and use any evidence discovered against him, Georgia v. Randolph, 126 S.Ct. 1515 (2006)(wife gave consent)

Probationer search allowed even though suspect's mother was present and objected to the search, Smith v. Santa Clara, 9th Circuit, 14-15103 (2017) 

d.   Knock & Talk - physically present occupant (woman) may give Consent to enter and search, even where previously present occupant (male) denied Consent but was now in jail , Fernandez v. California (2014)

e.   Knock & Talk - cites many cases and which doors Police approached, Carroll v. Carman (2014)(this is a civil case against Police). 

18.   TRAFFIC STOP - Police may stop a motorist with probable cause for a traffic violation, even if the Officer’s motive is to potentially solve another crime, Arkansas v. Sullivan, 121 S.Ct. 1876 (2001).

However, Federal Police may not use Race or Ethnicity in making a decision to make routine traffic stops, Guidance Regarding the Use of Race by Federal Law Enforcement Agencies, U.S. Department of Justice, 2003.

 For all Police, the U.S. Constitution prohibits selective enforcement of law based on considerations such as Race, Whren v. U.S., 116 S.Ct.1769 (1996).


a.   Safety & Regulatory Inspections – Police may conduct a sobriety checkpoint, license and registration checkpoint, border patrol checkpoint near border, and highway information checkpoint without reasonable suspicion (RS) or probable cause (PC), Illinois v. Lidster, 124 S.Ct 885 (2004).

b.   General Crime Control - Police may not stop cars at a roadblock for general crime control, e.g., drug checkpoint. Police must have Reasonable Suspicion or Probable Cause to stop a motorist for a crime or traffic violation, City of Indianapolis v. Edmond, 121 S.Ct. 447 (2000).

c.   Recent Serious Crime – Police may use a roadblock in an area Police reasonably know will be used by a fleeing criminal of a recent serious crime (e.g., kidnapping, escape, robbery, etc.). Police may stop all vehicles and search for victim(s) or suspect(s), LaFave §9.6a.

d.   Barricade to Stop Fleeing MotoristBrower v. County of Inyo, 109 S.Ct. 1378 (1989)(Police chased stolen car, placed 18 wheel truck across highway behind curve, turned on headlights to blind driver, driver killed after running into truck. Police Officers may be sued for unreasonable seizure).


a.   Of Container - to determine the presence of contraband, e.g., illegal drugs, Police may use a trained canine to sniff the exterior of lawfully seized personal property, e.g., suitcase at airport, U.S. v. Place, 103 S.Ct. 2637 (1983); if PC exists illegal drugs are inside, a SW or Consent is required to search the container.  

b.   Of Vehicle in Public - to use a trained canine to sniff a vehicle’s exterior for contraband during a lawful traffic stop no Consent or Warrant is required, Illinois v. Caballes, 125 S.Ct 834 (2005); if PC exists contraband, e.g., illegal drugs, are inside - no SW or Consent is required before searching the vehicle.

After traffic stop completed, Consent or RS required to conduct Dog Sniff, Rodriquez v. U.S., (2015)

c.   Of Residence front porch - to use a trained canine to sniff for contraband odors on a person's front porch requires prior use of Consent or a Search Warrant, Florida v. Jardines (2013)


If a probationer is knowingly subject to a full search condition, Police may conduct a warrantless search of the suspect’s premises based on reasonable suspicion, U.S. v. Knights, 122 S.Ct. 587 (2001).

Information from another Police Officer supports a probation search, Griffin v. Wisconsin, (1987)

Probationer Premises Search, U.S. v. Williams, 5th Circuit, 17-30198 (2018)

Probationer premises search allowed even though the suspect's mother was present and objected, Smith v. Santa Clara, 9th Circuit, 14-15103 (2017)

Probationer Cell Phone Search, U.S. v. Lara, 815 F.3d 605 (9th Cir. 2016)


If a parolee is knowingly subject to a full search condition, Police may search him without RS or PC, Samson v. California, 126 S.Ct. 2193 (2006).

Parolee Cell Phone Search, U.S. v. Pacheco, 10th Circuit, 16-3294 (2018)

Parolee Premises Search, U.S. v. Carvantes, 859 F.3d 1175 (9th Circuit 2017)

22.   PRIVATE SEARCH – The 4th Amendment is a restriction on Federal, State and local governments, not individuals. A private person, not acting as an agent for Police, who searches a house, vehicle, container, or file of a suspect may possibly violate State law but not the 4th Amendment.

a.   If the private person discovers criminal evidence he may give it to Police and the evidence may be used at Trial..

b.   However, Police may only examine that part of a container, file, film, CD or computer record the private person observed. Police must have a SW or the suspect’s Consent to search the evidence/property further than the private person did, U.S. v. Jacobsen, 104 S.Ct. 1652 (1984).

Private Search of Cell Phone, U.S. v. Highbull, 8th Circuit, 17-2728 (2018)

23.   VIDEO RENTAL RECORD – For Police to obtain the names of videos, CDs and DVDs rented by a suspect at a video store, a written Consent of the suspect, Search Warrant, Grand Jury Subpoena or Court Order is required, 18 U.S.C. § 2710, Video Protection Act.

24.   FIRST AMENDMENT & SPECIAL RELATIONSHIP SEARCHES- For all Police to obtain non-contraband evidence or information from a non-suspect First Amendment entity (radio station, T.V. station, newspaper, book store) Consent, subpoena or Search Warrant must be used - in that order, 42 U.S.C. § 2000aa, Privacy Protection Act. (For terrorism information, contact FBI / Patriot Act.)

For Federal Police to obtain non-contraband evidence from a non-suspect person with a special relationship with a suspect (physician, lawyer, religious minister) Consent, subpoena, or Search Warrant must be used in that order.

Back To Index Page