(Reuters) - The Supreme Court of Arkansas on Friday struck down that state's execution law in a split decision that sided with a group of 10 Death Row inmates who had argued only the state legislature can set execution policy.

The decision came in a lawsuit filed in 2010 by Death Row inmate Jack Harold Jones against the head of the Arkansas Department of Correction.

Jones, who was joined in the suit by nine other inmates, argued that a 2009 law giving the department and its director authority to choose the chemicals administered in executing inmates by lethal injection violated the state's separation of powers between the legislative and executive branches.

The court, with two justices dissenting, agreed and ruled the law unconstitutional.

(Reporting By Dan Burns; Editing by Vicki Allen)