Yesterday, TruTV’s Dan Abrams hosted discussions of last year’s trial of Mark Jensen, which included testimony of his then-current wife Kelly Jensen about what the couple did before their marriage, namely, cheated on his wife at the time, the decedent and his supposed victim, Julie.

One of the prosecutors phoned in an interview in which she explained why the current wife had not been entitled to claim “spousal privilege” to avoid testifying against Jensen. Specifically, the state was entitled to force her to testify about emails passed between the couple before they were married.

What is a privilege?

A privilege is a right granted to a person by a jurisdiction in order to further the common good. It is not an inherent right of citizenship. (At least, that’s how I “read” it, but I am not a lawyer.) Most privileges involve privacy rights to communications between two people. These include privileged communications between doctor and patient, lawyer and client, priest and confessor, and married people. Spousal privilege is not a “spousal right” because it isn’t absolute: there are many exceptions.

Which spouse owns the privilege?

In the spousal privilege, the primary privilege-holder is the originator of the communication, but the receiver also has some rights. Apparently, each state has very different statutes on the issue. In some states only one spouse is entitled to assert the right; in other states both.

In addition, the privilege exists only in state-recognized unions. In most states that means a traditional marriage certified by a marriage license, not common-law marriages and certainly not roommates or significant others. (Obviously, in states that do not permit same-sex marriages, such marriages are also not entitled to the spousal privilege—something to consider.)

It’s an interesting privilege, isn’t it?

The privilege does not cover crimes against the other spouse (spouse abuse) nor against their children (child abuse) nor is it applicable to civil litigation, such as divorce.

Spouses are not protected from being required to testify about events or communications that took place in public (in the presence of a third party). (I wonder if that includes whispering in your spouse’s ear at a crowded party.)

Given this limitation, I’d love to know more about the Crawford v Washington case, which led to the Supreme Court’s clarification of the Sixth Amendment right to confront one’s accusers (and which is expected to play a role in Jensen’s appeal). In the original trial, the defendant claimed he had justifiably stabbed a man to defend his wife against a rapist. He claimed spousal privilege, and so his wife did not testify at the trial. However, she had given a taped interview to authorities after the incident, and the tape was played at the trial.

The Supremes found that playing the tape without putting the wife on the stand violated the defendant’s Sixth Amendment rights.

What I don’t understand is why spousal privilege prevented the spouse from testifying about events that took place in the presence of a third-party, the stabbing victim.

However, I do understand why Wisconsin didn’t charge Kelly Jensen as an accomplice: it would have given her the right not to testify and incriminate herself. As long as she was only a witness, she could be forced to discuss those incriminating emails. (Is this a rare, good use of computer forensics evidence against a defendant?)

All this is grist for the fiction mill, isn’t it? It also illustrates why I find criminal trials so interesting and simultaneously frustrating: Judges and prosecutors stretch and twist the letter of the law in order to throw bad guys in jail.

Jurors are only pawns in the chess game. We should rejoice every time a jury hangs. That’s when the system provably works.

• Sidebar: For a clear explanation of spousal privilege, turn to lawyer Leslie Budewitz, who’s also a writer of English (not legalese) and a Sister in Crime. West’s Encyclopedia of American Law is a bit more technical—but also more expansive—than Ms. Budewitz’s.