Yes, evidence can be excluded later, but it is important to understand exactly how that works, because the Article 32 hearing does not itself exclude evidence from trial. An objection made during the preliminary hearing does not produce a ruling that keeps the evidence out of the court-martial. Exclusion is decided later, by the military judge, on a proper motion. What the Article 32 objection does is help build and preserve the record that supports that later motion. This article untangles the relationship between objecting at the preliminary hearing and getting evidence excluded at trial.
The preliminary hearing officer does not rule the way a trial judge does
The Article 32 preliminary hearing, governed by Article 32 of the Uniform Code of Military Justice and Rule for Courts-Martial 405, has a narrow job: to assess probable cause, confirm that the specifications state offenses, confirm jurisdiction, and make a disposition recommendation. It is not a forum for deciding the admissibility of evidence at trial.
Only a limited set of the Military Rules of Evidence applies at the preliminary hearing, principally privileges, the rape-shield rule, and the privilege against self-incrimination. For everything else, the broad admissibility rules are not fully in play. Just as significant, the preliminary hearing officer is not required to rule on objections. When a party objects, the officer can simply note the objection on the record and move on, considering the evidence anyway for purposes of the probable-cause determination. So an objection at the Article 32 hearing does not, and is not meant to, exclude the evidence even from the hearing itself, let alone from trial.
Exclusion happens at trial before the military judge
The place where evidence is actually excluded is the court-martial, through a motion to the military judge. Whether the issue is an unlawful search, an involuntary statement, an authentication problem, or a rule-based objection such as hearsay or relevance, the defense raises it as a pretrial motion or motion in limine, the full Military Rules of Evidence apply, and the judge issues a binding ruling. These motions are ordinarily made before pleas are entered, and a known issue that is not raised at the proper time can be forfeited.
This is why the answer is yes, evidence can be excluded later: the trial judge has the authority the preliminary hearing officer lacks. The objection at the Article 32 hearing is a step along the …