(New throughout, add national implications, comments from legal experts)
By Heide Brandes and Jon Herskovitz
March 26 (Reuters) - An Oklahoma judge ruled on Wednesday the state's secrecy on its lethal injections protocols was unconstitutional, a decision that could delay executions in other states where death row inmates are planning to launch similar challenges.
County district court judge Patricia Parrish ruled the state violated due process protections in the U.S. Constitution by not providing the name of the drug supplier, the combination of chemicals and the dosages used in executions.
Oklahoma's attorney general said the office will appeal.
Oklahoma and other U.S. states have been struggling to obtain drugs for executions. Many pharmaceutical firms, mostly in Europe, have imposed sales bans because they object to having medications made for other purposes used in lethal injections.
The states have looked to alter the chemicals used for lethal injection and keep the suppliers' identities secret. They have also turned to lightly regulated compounding pharmacies that can mix chemicals.
But lawyers for death row inmates argue drugs from compounding pharmacies can lack purity and potency and cause undue suffering, in violation of the U.S. Constitution.
"Judge Parrish's decision is a major outcome that should have a reverberating impact on other states that are facing similar kinds of transparency issues," said Fordham Law Professor Deborah Denno, who specializes in the legalities if lethal injections.
The Oklahoma case was brought by lawyers for two inmates, Clayton Lockett and Charles Warner, who were due to be executed this month. Their sentences were pushed back until April because the state said it could not obtain the drugs it has used for years in its lethal cocktail.
In response, Oklahoma last week proposed a protocol that would allow the Department of Corrections to choose from five potential lethal injection combinations, according to court documents.
Legal experts expect more states to face challenges that will delay executions, but if they settle transparency issues, many will resume putting inmates to death.
"Almost every state is hiding part of the process, or is attempting to," said Richard Dieter, the executive director of the Death Penalty Information center, a monitoring group for the implementation of capital punishment.
"Ultimately what will happen is that states have to reveal more information and that necessarily won't be a bad thing," Dieters said.
For now, several of the 32 states with the death penalty are keeping mum about business transactions for execution drugs.
Texas, which has executed more prisoners than any other state since the U.S. Supreme Court reinstated the death penalty in 1976, has obtained a fresh batch of the drug it uses for its executions.
But Texas will not identify the supplier, citing "previous, specific threats of serious physical harm made against businesses and their employees that have provided drugs used in the lethal injection process," the Texas Department of Criminal Justice said in a statement.
Alabama said this week it has run out of one of the main drugs it uses, putting on hold executions for 16 inmates who have exhausted appeals and face capital punishment. It is also looking at ways to keep the name of drug providers secret.
Inmates in Missouri, which carried out an execution this week, have sued the state over execution protocols that include layers of secrecy.
Arizona said on Wednesday it had to change its lethal injection cocktail because it could not obtain the drugs it once used.
"Being lost in the conversation and political maneuvering is the fact that family of murdered loved ones are paying the ultimate price as they wait for justice to be carried out," Arizona Attorney General Tom Horne said in a statement. (Additional reporting by Verna Gates in Birmingham, Alabama; Writing by Jon Herskovitz; editing by Gunna Dickson and David Gregorio)