State v. Simpson, 2011 Ohio 2771

In the early hours of February 1, 2010, Patrick Sullivan was severely assaulted in his basement bedroom at 1556 Tonawanda Ave, by Simpson, Frano, Moran, and Hackney.
Sullivan suffered multiple severe injuries, including skull fractures, a broken nose, and internal damage requiring a colostomy, with hospitalization and transfer to a nursing home.
Frano testified he pled guilty to felonious assault and testified against Simpson; Moran was not charged but admitted involvement inconsistently.
Simpson was indicted for rape, felonious assault, and tampering with evidence; at trial, he denied participation in the basement assault.
The jury found Simpson guilty of felonious assault and tampering with evidence, but not guilty of rape; he was sentenced to four years for felonious assault and one year for tampering, to run concurrently.
On appeal, Simpson argued the trial court failed to give a required cautionary accomplice instruction under R.C. 2923.03(D); the court of appeals reversed on that ground and remanded.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the trial court erred by omitting the R.C. 2923.03(D) accomplice cautionary instruction	Simpson contends the omission prejudiced the defense by diluting accomplice credibility.	State argues the error was not plain and the accomplice's testimony was corroborated enough to sustain the verdict.	Yes; plain error found and the judgment reversed.

State v. Davis, 2005-Ohio-4083 (9th Dist. 2005) (plain-error framework for accomplice instruction)