Washington - The US Supreme Court ruled Thursday that convicted criminals do not have the constitutional right to demand DNA testing, a relatively new technology that has overturned the convictions of more than 200 people.

In a 5-4 decision, the highest US court said it was up to individual states to decide how they would deal with the new technology. Forty-seven states already have laws that give convicts at least some access to genetic evidence.

DNA testing has exonerated 240 people since the early 1990s, including some who had been sentenced to death, according to the Innocence Project, a US group that lobbies for the use of genetic evidence.

The case before the Supreme Court involved William Osborne, an Alaskan man who was convicted of a brutal rape and attack on a prostitute in 1993. Osborne later sought DNA testing of a condom used in the attack, which he said would prove his innocence or guilty.

Alaska, which has enacted no laws on using DNA evidence, denied his request to have the condom tested. The Supreme Court said Osborne had no constitutional right to get a DNA test, and pointed out that Osborne had admitted to the crime during a parole hearing in 2004.

"DNA testing has an unparalleled ability both to exonerate the wrongly convicted and to identify the guilty," Chief Justice John Roberts acknowledged in the ruling, which reversed a lower court decision.

"The availability of new DNA testing technologies, however, cannot mean that every criminal conviction, or even every criminal conviction involving biological evidence, is suddenly in doubt," Roberts wrote.

Peter Neufeld, co-director of the Innocence Project, called it a "deeply flawed and disappointing decision" but said it would have a limited effect.

"In the vast majority of cases, prisoners are granted DNA testing under state law or because prosecutors consent to testing without a court order. That will continue to happen," Neufeld said.(dpa)