Key Words, Doctrines, Phrases, and Concepts
Reasonable Suspicion (RS) is a lower barrier than probable cause (PC). RS must 1) be justified at inception, and 2) justified in scope. There must be a particularized an objective basis for suspicion, it cannot merely be a hunch, and the suspicion must be a common-sense conclusion that practical people would reach and rely on.
Avert the Eyes
Police need not shield their eyes when in/on public areas, like public roads.
If in public, and have something in a closed container, police cannot just open it EXCEPT when either 1) consent is given, 2) it's an exigent circumstance, 3) when the container is in an automobile and there is PC, 4) SILA, or 5) officer has a warrant.
Probable Cause Definition
The Supreme Court standard of probable cause is whether "the facts and circumstances before the officer are such to warrant a man of prudence and caution in believing that the offense had been committed." (Stacey v. Emery).
High Crime/Drug Area
High crime areas are among the relevant contextual considerations police may consider when thinking about reasonable suspicion and probable cause (Illinois v. Wardlow).
Nervous, evasive behavior is a pertinent factor in determining reasonable suspicion. It's not indicative of wrongdoing, but it is suggestive. (Illinois v. Wardlow).
Experience of Officer
Police may partially rely on their professional experience in determining whether an act is suspicious (Terry v. Ohio).
Fruit of the Poisonous Tree
In most cases, if evidence is a result of constitutional violations, then the evidence is suppressed.
Defying Regulations/ Rules
Arguing about defying regulations and rules does not appear to have a particularly strong effect on the Court if the law is broken (Whren).
Joint Suspicion/ Joint PC
If it's reasonable to infer, based on the facts, that any or all of the suspects knew about and controlled the contraband, then officers have PC to arrest them all (Pringle).
Using an Alias
Using an alias contributes to RS. It's not conclusive, but it warrants suspicion (Sokolow).