Law-abiding citizen see the need for police to sometimes detain, question and even arrest, but the idea that authorities can possess an innocent person -- or even take a microscopic piece of one -- is not equally accepted.
Americans, says the Fourth Amendment, have a right to be "secure in their persons, houses, papers, and effects against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause."
The Supreme Court recently had to redefine warranted searches in an age when swabbed DNA can be planted in a database as a tracer for anywhere a body might spill something, for any reason, for the balance of a lifetime.
The Court upheld a Maryland law requiring people arrested for violent crimes to undergo a DNA swab. A similar law is now being considered in the Pennsylvania Senate.
Law and order enthusiasts naturally see opportunity here to solve cold cases that have had few leads for years or, maybe, right some situations where the justice system went wrong.
Others -- including four of the nine justices on the high court -- see it as a clear violation of the Fourth Amendment, which protects citizens from unreasonable searches and seizures, which they took to include their molecules.
The majority, represented by Justice Anthony Kennedy, focused on the "need for law enforcement officers … to identify the persons and possessions they must take into custody" as if DNA tracking was mainly to sort out who's who and who's where, the police equivalent of an organized sock drawer.
Justice Antonin Scalia wrote in the dissent that the Maryland law isn't to help law enforcement officials directly solve the crime being currently investigated, but rather the cold-case crimes. It is more like keeping you forever at the police station, in case you wander off the straight and narrow some decades hence.