OKLAHOMA CITY, Okla. – Gov. Kevin Stitt signed a new law cracking down on unreliable jailhouse informants – incarcerated witnesses who testify in exchange for leniency in their own cases. Four wrongful convictions in Oklahoma involved false jailhouse informant testimony, including Ron Williamson and Dennis Fritz, whose cases were featured in John Grisham’s book and documentary “The Innocent Man.”

The new law, sponsored by Sen. Julie Daniels (R-Bartlesville) and Rep. Chris Kannady (R-South Oklahoma City), will make Oklahoma the third state in the country to establish statewide tracking of jailh...