San Francisco ? A federal judge ruled Tuesday that California must change its lethal injection method for an execution next week, saying the current mix of drugs may constitute cruel and unusual punishment.

U.S. District Judge Jeremy Fogel said he was concerned inmates are conscious and undergoing extreme pain during execution.

The usual lethal injection method involves giving a sedative, a paralyzing agent and then a heart-stopping drug. Fogel ordered the state to either have an expert present to ensure Michael Morales is unconscious from the sedative, or replace a three-drug mix with a lethal dose of barbiturate.

Morales is scheduled to be executed Tuesday for the rape and murder of a 17-year-old girl 25 years ago.

His attorneys alleged a mistake in the sedation process might mean he would appear unconscious, but internally would succumb to excruciating pain.

Fogel said he decided to change the method because, neither “the death penalty nor lethal injection as a means of execution would be abolished.”

If the state declines to choose either new option, Fogel said he would stay the execution.