It’s had an impact:
In “The Decline of the Death Penalty and the Discovery of Innocence,” political scientists Frank Baumgartner, Suzanna DeBoef and Amber Boydstun found that since the mid-1990s, news coverage of the death penalty has increasingly focused on exonerations and wrongful executions. In earlier eras, the debate in the media was more frequently about other issues, such as capital punishment’s constitutionality or cost.
This shift in media coverage, which has highlighted problems in the death penalty’s application, has encouraged the public to evaluate capital punishment in terms of fairness, especially the potential for innocent people to be sent to death row. As a consequence, Baumgartner, DeBoef and Boydstun find that along with a decline in the U.S. murder rate and other high-profile events (such as former Illinois governor George Ryan’s (R) 2001 mass commutation of death row inmates), negative news drove down support for capital punishment.
How much did public opinion move? By one measure, 86 percent of Americans in 1995 said they favored the death penalty for people convicted of murder. But by 2006, just 70 percent did.