Final answer:
Claims of Fourth Amendment violations involving warrant-less seizures don't often succeed in lineup cases because they occur post-arrest under probable cause, don't involve a reasonable expectation of privacy, and concern physical evidence over testimonial. The need for a search warrant has exceptions like exigent circumstances, with landmark cases like Mapp v. Ohio defining the exclusionary rule and legal limits.
Step-by-step explanation:
Claims of violation of the Fourth Amendment regarding warrant-less seizures do not usually prevail in lineups and showup cases primarily because these procedures are typically carried out after a suspect has been arrested under probable cause. Moreover, at that stage, there is often no longer a reasonable expectation of privacy, which significantly limits the warrant requirement. Additionally, the evidence presented in lineups and showups is generally physical in nature, such as the suspect's appearance, rather than testimonial or communicative.
In situations where a search warrant is required, law enforcement officers must present probable cause to believe a crime has been committed or evidence will be found. However, there are exceptions to this requirement, including exigent circumstances, consent, and the plain view doctrine. Under certain conditions, such as when evidence is in plain view or an imminent threat exists that evidence could be destroyed, a warrant might not be necessary.
The principle is further supported by landmark cases such as Mapp v. Ohio and Katz v. United States, which solidified the exclusionary rule and the protections against unreasonable searches and seizures, but also acknowledged the constitutional allowances for searches without a warrant under specific circumstances, adhering to established exceptions.