G.R. No. L-10492; August 12, 1915
THE UNITED STATES, plaintiff-appellee, vs. YAO SIM, defendant-appellant.

FACTS:
The accused, Yao Sim, was found in possession of approximately 3 grams of opium. At trial, the prosecution presented competent evidence proving this fact of possession. The accused did not present any evidence to support a claim that his possession of the opium was lawful. On appeal, the defense argued that the conviction should be overturned because the prosecution failed to present affirmative evidence to negate the possibility that the accused was lawfully entitled to possess the opium for medicinal use upon a physician’s prescription.

ISSUE:
Whether the prosecution is required to present affirmative evidence to negate a statutory exception (lawful medicinal use) to an offense (possession of opium) once the fact of possession has been established.

RULING:
No. The Supreme Court affirmed the conviction. The Court held that once the prosecution has established the fact of unlawful possession of a prohibited drug by competent evidence, the burden does not shift to the prosecution to prove the negativethat the accused was not authorized to possess it for medicinal purposes. It is incumbent upon the accused, if he claims the benefit of a statutory exception (such as medicinal use upon a physician’s prescription), to present evidence to support that claim. Since the accused in this case offered no such evidence, the trial court correctly convicted him. The ruling is in line with the doctrine established in U.S. vs. Chan Toco (12 Phil. Rep., 262). The judgment of the trial court was affirmed, with costs against the appellant.