Nitrogen hypoxia, a method of execution Arkansas lawmakers are considering adopting, makes for a torturous death, witnesses say.

Executions using nitrogen gas will soon be legal in Arkansas if the governor signs the legislation into law. House Bill 1489 passed in the Senate on Tuesday. Having already cleared the House, the bill’s next stop is at the governor’s desk for signature.

As Arkansas moves closer to adopting nitrogen gas executions, the controversial method sparks intense debate over justice and humanity.