A waiver of the Article 32 preliminary hearing can significantly limit the scope of issues available for appellate review. By knowingly and voluntarily waiving the hearing, the accused gives up the right to challenge any procedural or substantive errors that might have occurred during that specific proceeding, because the proceeding itself never happens.
The Article 32 hearing is a primary vehicle for creating a factual record on pretrial issues. For example, if there is a question about the legality of a search or the voluntariness of a confession, the hearing provides the forum to question witnesses and develop evidence on the matter. By waiving the hearing, the defense forfeits this opportunity to build a record, which can make it much more difficult to litigate a motion to suppress later. The appellate court would have no hearing transcript to review for potential errors.
Furthermore, any claim that the evidence was insufficient to establish probable cause is effectively waived. The purpose of the hearing is to test for probable cause, and by skipping it, the accused concedes that the government has met this low initial threshold. An appellate court will not entertain an argument that the case should never have been referred to a general court-martial in the first place.
While a waiver does not prevent the accused from appealing other issues that arise during the trial itself, such as evidentiary rulings by the judge or errors in jury instructions, it permanently closes the door on any appellate claims related to the pretrial investigation phase. This is why the decision to waive is so significant and must be made with a full understanding of the appellate rights being relinquished.