John McLean, Stein v. Bowman — Opinion of the Court
“ The rule which protects the domestic relations from exposure, rests upon considerations connected with the peace of families. And it is conceived that this principle does not merely afford protection to the husband and wife, which they are at liberty to invoke or not, at their discretion, when the question is propounded; but it renders them incompetent to disclose facts in evidence in violation of the rule. And it is well that the principle does not rest on the discretion of the parties. ”
