Convicted prisoners have no constitutional right to biological evidence for DNA testing.
In a 5-to-4 ruling announced Thursday, the US Supreme Court declined to apply the protections of the Constitution's due process clause to the case of a convicted rapist in Alaska.
The high court said the case should be governed by state laws and state judicial rulings – not constitutional pronouncements from the Supreme Court.
"Establishing a freestanding right to access DNA evidence for testing would force us to act as policymakers," Chief Justice John Roberts wrote in the majority opinion.
The case was being closely followed because it offered the high court the opportunity to make a bold statement establishing a nationwide constitutional standard dealing with DNA evidence. The majority justices declined to do so.
"This approach would take the development of rules and procedures in this area out of the hands of legislatures and state courts shaping policy in a focused manner and turn it over to federal courts applying the broad parameters of the due process clause," the chief justice wrote. "There is no reason to constitutionalize the issue in this way."
The decision comes in the case of convicted rapist William Osborne, who was asking a judge to order new, more accurate DNA testing of the biological evidence used to convict him in 1993.
In a dissent, Justice John Paul Stevens said Mr. Osborne had demonstrated a constitutionally protected right to test the evidence used against him.
"The DNA test Osborne seeks is a simple one, its cost modest, and its results uniquely precise," Justice Stevens wrote. "Yet for reasons the state has been unable or unwilling to articulate, it refuses to allow Osborne to test the evidence at his own expense and to thereby ascertain the truth once and for all."
DNA testing has been called the most important advance in the history of forensic science because it often can conclusively determine guilt or innocence. Post-conviction DNA testing has freed 227 individuals, 17 of whom faced death sentences.
Forty-four states and the federal government have laws establishing procedures to conduct DNA testing. Alaska is one of six states with no such law.
Trial procedures in Alaska allow for DNA testing prior to trial or within the usual appeals process, but the state restricts post-conviction access to biological evidence in other contexts.
Alaska officials refused to grant access to the biological evidence in Osborne's case. The Alaska courts upheld that judgment. But a federal judge and a panel of the Ninth US Circuit Court of Appeals ordered the state to allow the new tests.
In reversing the Ninth Circuit, the majority justices said the appeals court went too far in applying broad constitutional safeguards firmly established in the context of a trial to Osborne's attempt to examine state evidence after his conviction.
Roberts said efforts to establish DNA evidence rules are best left to legislatures and state courts.
"If we extended substantive due process to this area, we would cast [existing state] statutes into constitutional doubt and be forced to take over the issue of DNA access ourselves," the chief justice wrote. "We are reluctant to enlist the federal judiciary in creating a new constitutional code of rules for handling DNA."