Local ordinances may empower police officers to make an arrest for a curfew violation.

When a court finds as a matter of law that the evidence, in the light most favorable to the Commonwealth, is not sufficient to support the verdict, the court should grant a motion for a judgment of acquittal. If this motion is granted after the jury has returned a verdict of guilt, then it is reviewable on appeal, since reinstating the jury verdict does not offend the proscription against double jeopardy.

A "seizure" under the meaning of the Fourth Amendment is not effectuated at the time that an officer merely orders a person to stop, but only occurs only after the application of physical force or submission to a show of authority by the police.

A defendant who sits on a landing in front of an apartment's locked door without a key cannot be found to have constructively possessed drugs found inside the apartment, in the absence of evidence that the defendant had ever been in the apartment.

A criminal defendant is presumed competent to stand trial and must prove his or her incompetency by a preponderance of the evidence. This applies even in cases where the court has ordered a mental health examination sua sponte.

A defendant's Fifth Amendment rights are violated by the admission of psychiatric testimony relaying incriminating statements in a trial where the defendant does not present a defense of diminished capacity. Even if statements had been offered in a previous trial to rebut a defense of diminished capacity in that previous trial, they are not admissible in a later trial where diminished capacity is not at issue.

"[W]hen a defendant demonstrates to the trial judge that his [or her] sanity at the time of the offense is to be a significant factor at trial, the State must, at a minimum, assure the defendant access to a competent psychiatrist who will conduct an appropriate examination and assist in evaluation, preparation, and presentation of the defense."

Pursuant to 18 Pa. C.S. § 315(a), in order for insanity to constitute a defense, a defendant must prove insanity by a preponderance of the evidence.

The test for competence to stand trial is "whether [the defendant] has sufficient present ability to consult with their lawyer with a reasonable degree of rational understanding – and whether [the defendant] has a rational as well as factual understanding of the proceedings against him."

While the prosecution must prove every element of every offense beyond a reasonable doubt, certain defenses, like that of insanity or extreme emotional disturbance, do not necessarily negative an element of the offense. Therefore, it is constitutional to shift the burden to the defendant to prove these types of defenses, and the defendant may be burdened with proving the defense beyond a reasonable doubt.