What is the only legal restriction for obtaining physical evidence from an arrested person?

The correct answer highlights that the method of seizure cannot be considered shocking. This underscores the legal principle that any seizure of evidence from an arrested person must comply with constitutional protections against unreasonable searches and seizures, as set forth in the Fourth Amendment. If the methods used to seize evidence are considered excessively intrusive or abusive, they can be deemed unconstitutional. Thus, law enforcement must balance their need for evidence with the rights of the individual, ensuring that their approach is reasonable and respectful of personal dignity.

In this context, while evidence being in plain view is a common principle that affirms when evidence may be seized without a warrant, it does not exclusively address the manner in which the evidence is collected from an arrested individual. The notion of consent plays a pivotal role in various legal contexts, but it is not an absolute requirement for obtaining evidence under arrest circumstances, especially if the evidence is observable or if it fits exceptions to normal consent requirements. The necessity for a witness at the scene, while potentially beneficial for documenting the process, is not mandated by law as a restriction for the legality of the evidence seizure.