The court on Tuesday rejected the appeal of the rapper known as C-Murder, who is serving a life sentence for killing a 16-year-old fan in Louisiana. A jury voted 10-2 to convict the rapper, whose real name is Corey Miller.
Louisiana and Oregon are the only two states that allow for non-unanimous convictions for some crimes.
The justices recently have rejected similar appeals asking them to treat state and federal trials equally. Decisions involving gun rights and other issues generally require states to extend the same constitutional rights as the federal government.