Arbitrariness and disparity in criminal law are fundamentally unfair and may lead to unjust convictions. In Texas, it already has. The Texas Court of Criminal Appeals could fix a striking disparity in Texas law in different parts of the state through two cases pending before it: Ex parte Andrew Roark, from Dallas County, and Ex parte Robert Roberson, from Anderson County. Roark and Roberson were both convicted of injuring children more than two decades ago based on a theory known as “shaken baby syndrome” and “abusive head trauma.” The same prosecution expert testified in both trials. Some new research shows, however, that evidence of “shaken baby syndrome” is not as reliable as courts, police and medical professionals used to believe.