"If we wanted to solve all of the crimes, make everybody in the country provide DNA," Starger said. "We would have the so-called universal database, but people would say instinctively, 'Well, I don't want that. That's an invasion of my privacy.'"
Gansler, who as state's attorney for Montgomery County used DNA evidence to prosecute a man who wore a mask, beat and raped a woman, said Supreme Court precedent is on the side of law enforcement. The high court allows individuals who are arrested to be handcuffed, patted down, and subjected to a body cavity search, he noted. Law enforcement "certainly can touch a cotton swab to the inside of the defendant's cheek for a second," he said.
Starger, however, notes that the Supreme Court in 2009 limited the use of DNA by ruling that prisoners do not have the constitutional right to use their genetic information to prove their innocence after a conviction. At the heart of the case was the guarantee of due process, access to DNA evidence and the limited rights available to a criminal proved guilty at a fair trial.
The high court left up to the states and Congress the determination of who has a right to the post-conviction testing. Every state, except Oklahoma, as well as Congress, now allows the testing.
In the 5-4 decision, Roberts, the chief justice, acknowledged the "challenges DNA technology poses to our criminal justice systems and our traditional notions of finality," which he said should be left in the hands of elected officials, rather than judges.
To many advocates, the matter is as simple as seeing DNA as a 21st-century fingerprint, used in crime-fighting since the late 1800s.
Maryland wrote in its brief, "Indeed, even absent a Fourth Amendment seizure, a person has no right to refuse to disclose identifying physical traits" such as voice, handwriting or hair samples.
"A person who is arrested for a violent crime has no right to withhold his identity from the police, and under the statute, the only information being analyzed by the state goes to the arrestee's identity," the state said in the brief. "Whether that identifying information is a photograph, series of whorls and ridges on a fingerprint, or the string of numbers resulting from a DNA profile, the collection of that information as a part of routine booking procedures is reasonable.
"King could give a false name; he could even change his appearance. But what King could not do is change the 26-number sequence derived from his DNA."
But King's public defender argued in a brief filed to the high court that law enforcement did not take King's genetic information to identify him in the 2009 assault; "it did so to determine whether he was implicated in any other offenses."
Attorneys for King, now 30, contend that the primary purpose of fingerprinting a person during their booking is to identify them, not investigate them for unsolved crimes. Giving the government access to "a vast genetic treasure map," as DNA has been called, on the promise it won't be misused is unheard of, they wrote.
"This court has never blessed a search that would otherwise violate the Fourth Amendment simply because law enforcement has promised not to review the information it obtains from the search in a particular manner," the public defenders wrote.
Baltimore Sun reporter Ian Duncan contributed to this article.
By the numbers
Maryland law enforcement began collecting DNA samples from individuals after their arrest in January 2009.
•225 Number of matches returned from a search of the evidence database for a previously unsolved crime
•73 Of those matches, number of offenders arrested for a subsequent crime:
•43 Of those arrests, number of convictions for the previously unsolved crime (including 29 burglaries and thefts, eight rapes and sex crimes, and four robberies)
Source: Governor's Office of Crime Control and Prevention