Houston-based attorney Martin Siegel, who specializes in appellate law, says it's a matter of sovereign immunity.
"In order for inmates to sue states for money damages, Congress had to have been more explicit in allowing those kinds of suits, because ordinarily states have what's called sovereign immunity. And in this case, the Supreme Court has held that the federal statute was not clear enough in providing for money damages in suits by incarderated people."
Sossaman had claimed he lost religious freedom while being kept in special confinement.
"The prison chapel could not be used for religious services, and also a restriction in prison that prevented his free exercise of religion when he was suject to special disciplinary restrictions."
The Supreme Court says monetary damages cannot be recovered, but the decision doesn't affect the ability of inmates to sue to change prison policies.