Trial courts may not create mandatory presumptions which relieve the prosecution of its burden to prove facts to the jury beyond a reasonable doubt. (Sandstrom v. Montana (1979) 442 U.S. 510.) Appellant was charged with murder and an enhancement for discharge of a firearm in commission of a felony. In the commission of the offense, appellant chased the victim, discharged a flare gun at him, without injuring him, but then caught up to him and stabbed him, inflicting four dozen stab wounds, and killing him. The court instructed the jury that as a matter of law a flare gun was a firearm. With this instruction, the court denied appellant due process by taking a critical issue of fact away from the jury in violation of clearly established constitutional law.