It took almost 90 minutes to carry out the execution of Joseph Clark in May 2006. The lawsuit, filed in a Cincinnati federal court, said the execution amounted to unconstitutional cruel and unusual punishment. Executions last about 20 minutes on average.
The prisons department declined to comment because officials have not yet seen the lawsuit, spokeswoman Andrea Dean said.
In a separate lawsuit, a group of 15 inmates are challenging the state's injection process, arguing the procedure may cause prisoners to suffer during an execution.
Prison staff had problems finding a useable vein on Clark, and one vein they did use collapsed. The execution team also apparently tried to administer the lethal drugs through the original IV line by mistake, according to written accounts that the execution team is required to submit.
During the first injection attempt, Clark finally pushed himself up and said, "It don't work."
During the second attempt at finding a vein, he asked, "Can you just give me something by mouth to end this?"
Clark, 57, was sentenced to die in November 1984 for killing gas station attendant David Manning in Toledo.
The problems during the execution led the state to change its lethal injection process to ensure that veins can be found more carefully and quickly to avoid similar delays.
But in May, an execution team again struggled to find veins in another inmate's arm. Christopher Newton died nearly two hours after the scheduled start of his execution.