Three days before Pennsylvania's next scheduled execution, an expert witness is raising concerns in federal court in Harrisburg about how the death penalty is carried out.

Dr. David Waisel, an anesthesiologist at Children's Hospital in Boston, testified Monday in a hearing in a 5-year-old class-action lawsuit challenging the constitutionality of the state's execution protocol on behalf of all 200 death-row prisoners.

Waisel questioned the training and experience of members of the "lethal injection team." He also said potentially confusing color codes on the drugs could unnecessarily cause excruciating pain for the inmate.

Fifty-six-year-old Hubert Michael Jr. would be the first person executed in Pennsylvania in 13 years if he's put to death as scheduled Thursday. He pleaded guilty in the 1993 shooting death of a teen-age girl in York County.