The lethal injection debate unfolding in California this week has garnered a lot of attention because of the medical ethics questions it brings up. But all along, the most interesting question for states has been what effect, if any, the federal ruling questioning lethal injection's constitutionality will have on their death penalty procedures.

The issue of whether lethal injection violates the constitutional prohibition against cruel and unusual punishment has only come to the surface recently, and is likely to garner a lot of scrutiny in the next few months as California reexamines its procedures and if the U.S. Supreme Court takes up the issue.

Not only could the high court decide to review California's ruling but it could also decide to review a Tennessee Supreme Court decision that upheld the constitutionality of that state's lethal injection protocol.

About 37 states rely on lethal injection, and challenges to its constitutionality are expected to multiply after this week's events. With so many different outcomes possible in federal courts across the country, it is hard to see how the high court could avoid reviewing the case. If the court found lethal injection cruel and unusual -- which many legal analysts say wouldn't happen -- the ruling would in effect leave most states without a lawful means of carrying out the death penalty.

In that case, a lot of states that are already questioning the issue will take an even closer look into its legality.