Should prisoners be able to sue if their rights are violated?

Prisoners must be allowed to sue if their rights are
violated.  If they could not sue, there would be no incentive for the state or federal
prison systems to respect prisoners' rights.

An example of
this can be seen in the recent Supreme Court decision about prison overcrowding in
California.  If prisoners truly are being held in conditions that are inhumane, they
need to have some way to rectify the situation.  If they could not sue, they would need
to rely on elected officials to push prisons to alleviate the problems.  This would
surely never happen because prisoners are not a sympathetic group.  Therefore, prisoners
who could not sue would have no way to force authorities to respect their
rights.