What do legal and factual insufficiency mean on appeal? Can my case really be overturned on appeal based on these concepts?

Yes.  A convicted appellant may find relief on appeal by arguing that the proof provided by the government during his court-martial was legally and/or factually insufficient to support the conviction he received.  Legal insufficiency means that a reasonable fact finder (court-martial panel or military judge) could not have found that the proof presented met the essential elements of the offense beyond a reasonable doubt.  Factual insufficiency means that the appellate court, after weighing the evidence presented at the court-martial and making allowances for not seeing the witnesses first hand, is not convinced that the appellant is guilty beyond a reasonable doubt.  Recently, the Army Court of Criminal Appeals (ACCA), in U.S. v. Hardin reversed an appellant’s conviction for housebreaking.  The ACCA found that while the evidence was legally sufficient to support such a conviction, it was factually insufficient.  This case involved an alleged sexual assault where the alleged victim asserted that appellant entered her room while she was sleeping without permission.  The appellant was found not guilty of the sexual assault offenses at the court-martial, but was found guilty of housebreaking due to not having permission to enter her room.  Among other facts presented, the ACCA reviewed the facts that the alleged victim had permitted the appellant to enter her bedroom earlier that evening on two occasions and then did not lock her door after that.  After weighing those facts and others, the ACCA reversed the conviction for housebreaking based on factual insufficiency.  If you believe that the court-martial conviction you or a loved one received was either legally or factually insufficient (or both) you may have a valid appeal.  I have a vast amount experience in court-martials and court-martial appeals.  Call me for a free consultation and we can discuss the specific circumstances of the case.  To speak to an experienced court-martial and military defense attorney, call Bill Cassara at 706-860-5769 for a free consultation.