To opponents, inmate labor is both a potential human rights abuse and a threat to workers outside prison walls.

The main prison building, a red-brick structure, was constructed by inmate labor.

At the same time, revenue from the prison farm and inmate labor helped the prison financially.

While inmate labor was an effective cost-cutting tool, it also gave the men an opportunity to learn a "useful trade."

The system used inmate labor to assist with the construction of the fence.

The building was constructed entirely of stone quarried on site and built mainly with inmate labor.

And California voters recently approved a proposition that would allow private employers to contract for inmate labor in the country's largest prison system.

Discusses sources of federal and state civilian inmate labor.

During those early years, inmate labor performed most of the work.

Nationwide, inmate labor sometimes arouses resentment from unions and local contractors.