OKLAHOMA CITY (AP) — Since the days of frontier justice, lawmakers in conservative Oklahoma have viewed harsh prison sentences as the politically expedient solution to crime, including nonviolent offenses.

That approach has imposed a high price, leaving the state with the nation's highest incarceration rate, overcrowded prisons and skyrocketing costs. Now, after years of steady debate, there's growing agreement — even among conservatives — that changes are needed.

But the fragile consensus has crashed headlong into a towering obstacle: the entrenched ideology of the state's top prosecutors, ma...