Suppression Motion may be filed by defense attorneys in order to keep out evidence.  One type of suppression motion deals with the Spoilation of evidence which deals with the intentional or unintentional destruction of evidence by the government-typically the police. Under Pennsylvania state law, police investigators are not required to keep rough notes from their investigation. This rule differs from Federal Law and the Jencks Act, know your Miranda rights where federal investigators are required to keep much more information that they obtain as a result of their investigations. Currently, in Pennsylvania there is no rule that the police preserve all evidence taken or all notes ever taken during their investigation because there might be some evidence which turns out to be exculpatory (tending to show that the defendant is innocent).

The Pennsylvania Rules of Criminal Procedure deal with issues of the spoilation of evidence and/or the turning over of evidence to the accused in a criminal case after the Preliminary Hearing. Specifically, the PA Rules of Criminal Procedure rule 573(B)(f) states in regards to the discovery of evidence by the defense that is in the possession of the government:

In all court cases, on request by the defendant, and subject to any protective order which the Commonwealth might obtain under this rule, the Commonwealth shall disclose to the defendant’s attorney all of the following requested items or information, provided they are relevant to the instant criminal case and the charges that the accused is facing.  Suppression motion stop and frisk The Commonwealth shall, permit the defendant’s attorney to inspect and copy or photograph items such as tangible objects, including documents, photographs, fingerprints, or other tangible evidence when in possession of the government. The issue of spoilation arises when the government destroys evidence that the defense otherwise would have been permitted to review

In the Federal cases of Arizona v. Young blood , (1988) and California v. Trombetta , (1984), the United States Supreme Court found that a defendant enjoys constitutionally-guaranteed access to tangible evidence, such as blood and semen, in order to examine the evidence to see if he tends to show that he is innocent of the crimes that he is charged with. The federal cases also indicate that if evidence is destroyed by law enforcement accidentally or because they do not believe it has an value to the case then there is no due process violation.