FILE - This March 2019, file photo, provided by the South Carolina Department of Corrections shows the state's electric chair…
FILE - This March 2019 photo, provided by the South Carolina Department of Corrections, shows the state's electric chair in Columbia, S.C.

The U.S. state of South Carolina has introduced a law requiring death row prisoners to choose between firing squad and electric chair after a lack of lethal injection drugs halted executions for a decade. 

"This weekend, I signed legislation into law that will allow the state to carry out a death sentence. The families and loved ones of victims are owed closure and justice by law. Now, we can provide it," Governor Henry McMaster said on Twitter.  

McMaster, a Republican, wants to resume executions after a 10-year hiatus caused by a shortage of drugs used in lethal injections.  

Before the pause, death row inmates would choose between the electric chair and injection, with the injection being administered if no choice was made.  

The new law, signed Friday, makes the electric chair the default option if lethal injection is unavailable, and creates the alternative option of a firing squad. 

Local prisoner advocacy group the Incarcerated Outreach Network called the move "appalling, shocking, abhorrent," while the South Carolina branch of the American Civil Liberties Union said it was "about finding a new way to restart executions within a racist, arbitrary, and error-prone system." 

"South Carolina's criminal justice system makes mistakes," Frank Knaack, ACLU executive director for the state, said in a statement. 

"Yet, capital punishment is irreversible. ... Black people make up more than half of South Carolina's death row despite being only 27 percent of the state's population." 

The electric chair has not been used in South Carolina since 2008, and the last execution by lethal injection was in 2011, according to the state's Department of Corrections.  

South Carolina is the fourth U.S. state to allow death by firing squad, along with Mississippi, Oklahoma and Utah, according to the Death Penalty Information Center.  

Only three convicts have died before a firing squad, all in Utah, since the U.S. Supreme Court reinstated capital punishment in 1976, according to the center. 

An acute shortage of the deadly drugs used in lethal injections has lasted several years, as several major laboratories refuse to stock U.S. prisons to avoid being associated with the death penalty. 

Lethal injections are generally carried out by the administration of three substances in succession: the first induces a coma, the second paralyzes and the third stops the heart. 

But in several executions in recent years, the first drug failed to render prisoners fully unconscious, causing them intense suffering prior to death.