The purpose of the Preventing Pretrial Gun Purchases Act is to strengthen the background check system for firearm purchases. It aims to ensure that individuals who are legally prohibited from possessing firearms due to a court order related to their pretrial release are effectively prevented from acquiring guns. Key provisions of this legislation include the addition of a definition for "pretrial release order" in federal law, which clarifies that it refers to any court order governing the release of a person awaiting trial for a crime.