California could take a giant step closer to resuming executions when the state Supreme Court issues a highly anticipated ruling on a ballot measure to speed up the state's dysfunctional death penalty system.

The California Supreme Court will rule Thursday on a lawsuit challenging the constitutionality of Proposition 66, a push to "mend not end" capital punishment in California. The measure beat a competing initiative on the November ballot that would have abolished the death penalty.

Condemned inmates in California currently languish for decades and are more likely to die of natural causes than from lethal injection. There are nearly 750 inmates on death row and only 13 have been executed since 1978 — the last in 2006.

The California Supreme Court ruling comes as state officials face a Friday deadline to unveil a revised lethal injection drug protocol to execute inmates. The fight over the drug procedure, which is tied up in federal court, has been a significant obstacle to resuming the death penalty.

Proposition 66 aimed to expedite death sentences in part by setting a five-year deadline on court appeals. It now takes up to five years for death row inmates to get an attorney, and it can take upward of 25 years to exhaust appeals.

Proposition 66 would expand the pool of appellate lawyers handling capital cases and allow lower-level state courts — not just the California Supreme Court — to hear appeals.

Death penalty opponents agreed with Proposition 66 backers that the current system was broken. But they argued that the measure would lead to the appointment of incompetent attorneys and overwhelm courts. The result: Insufficient review that could send innocent people to their deaths.