It made me think about a real evidentiary issue in divorce cases, the Spousal Disqualification. This is not a privilege — privileges can be waived. It’s a disqualification to testify to the content of a discussion between spouses, if the spouses had a reasonable expectation the conversation would be private.
I think the disqualification was a result of the desire to treat marriage differently from any other relationship. Privileges exist with other relationships, for example patient/psychotherapist and lawyer/client, among others. However, in these relationships the privilege belongs to the patient or the client, and they alone can waive the privilege and the testimony will come in. This is not the case with spousal disqualification because both spouses have to agree to the waiver. In practice this happens by default; if one person offers the testimony and the other fails to object to the testimony, the disqualification is waived.There are also exceptions which arise often in divorce law, including proceedings arising out of or involving contracts between spouses; paternity and child support proceedings; non support, desertion or neglect proceedings; child abuse/incest proceedings; criminal proceedings involving one spouse victimizing the other; violation of a vacate, restraining or no contact order; and a couple of other circumstances which only apply in the criminal courts.
There are also ways to get around the disqualification if the judge allows (some do, some don’t). It often arises in divorce proceedings where one spouse has confessed to an affair to the other spouse. The attorney can have the spouse who wishes to testify describe where the parties were and whether or not any one could have overheard them. In a restaurant or a public place the expectation of privacy didn’t exist, and of course if the children were present or nearby it arguably didn’t exist either.