There are two parts to the rule. The spouse can refuse completely to testify, this is the spousal incapacity and the “privilege" belongs to the testifying spouse; or the spouse can be stopped from testifying about communications. In the second situation the spouse can still testify about acts she saw. So some examples.

A spouse agrees to testify about your drug offenses and she’s completely uninvolved. She tells the court that she saw you bring homes some drugs and hide them. And that’s where the CID found them in a search. That’s admissible. But what’s not admissible is what you said to her about where you got them and what you were going to do with them.

Caution. This rule is changed beginning in 2012. Prior to 2012, the rule had several exceptions, most importantly: (1) when the accused is charged with a crime against the person or property of the spouse or the child of either; and (2) when, at the time of the testimony is to be given, the marriage has been terminated by divorce or annulment. In at least one case the courts have given a broad interpretation, United States v. McCarty, 45 M.J. 334 (de facto family members may qualify, e.g., niece who lived with family for 10 years). This is inconsistent with the court’s holding in United States v. Custis, 65 M.J. 366 (C.A.A.F. 2007), and in my opinion is likely overruled by Custis. Custis is the case which lead to this new addition to the exceptions for the spousal privilege.

Caution: 2012 change adds the following exception to the privilege:

(a) M.R.E. 504(c)(2)(D) is added to read as follows:

Where both parties have been substantial participants in illegal activity, those communications between the spouses during the marriage regarding the illegal activity in which they have jointly participated are not marital communications for purposes of the privilege in subdivision (a) and are not entitled to protection under the privilege in subdivision (b) (emphasis added).

Keep in mind that if the spouse is also accused of similar crimes then the Fifth Amendment right to silence will apply to that spouse, so they can still refuse to testify on the basis of their Fifth Amendment right: unless they are given grant of immunity.

Keep in mind that there will be litigation whether the spouse is a “substantial participant." What exactly that means will be determined on a case-by-case basis. This should be addressed by your military defense lawyer in a motionin-limine.

Keep in mind that there will be litigation over when the spouse began to be aparticipant. That’s because, “"The majority of [federal] circuits agree that communications made before a spouse begins to participate in the criminal activity are privileged." " And apparently ACCA agrees. United States v. Davis, 61 M.J. 530 536 (A. Ct. Crim. App. 2005) pet. denied 62 M.J. 230 (C.A.A.F. 2005).

Keep in mind there will be litigation over the scope of the exception. Any testimony must be directly related to the specific illegal activity in which they have jointly participated. This should be addressed by your military defense lawyer in a motionin-limine.

Caution. Military courts consider adultery a crime against the other spouse, thus there is no privilege. United States v. Taylor, 64 M.J. 416 (C.A.A.F. 2007).