Except In cases of necessity the wife was incompetent to
testify for or against her husband at common law Coke
suggests that the reason for the rule lay in the fact that husband
and wife were one, and naturally could not be divided for the
purposes of testimony Although the courts soon got beyond this
doctrine, they insisted on the value of the rule. They argued that
spouses, though perhaps not physically identical, were identical
in interest. When disqualification by interest was removed, the
judges bad to take other ground, and did so in Stapleton v
Crofts.\u27 There they decided that the true basis for the rule was
the necessity of martial harmony and confidence.
But even this philosophy has been unable to sustain the noton
that one spouse cannot appear for or against the other. The
disqualification has gradually been reduced to a disqualification in
criminal cases alone. The dissenting opinion of Mr. Justice
Erle in Stapleton v. Crofts states the arguments that have prevailed
against broader disqualification. He points out that the
idea of promoting domestic peace is incapable of consistent application
in these cases. It is not applied to witnesses not parties
to the action. Mr. W may testify for the plaintiff, Mrs. W
against him. Their stories may lead to endless ructions in the
W household. Erle, J., doubts, too, whether husbands suborn
their wives to perjury He is reasonably sure that the exclusion
of the evidence is a definite loss, whereas the gain, if any, is remote
and speculative
