nor oppressive exercise of the police
power.[156]

Collective Bargaining.--During the 1930's, liberty, in the
sense of freedom of contract, judicially translated into what one
Justice has labelled the Allgeyer-Lochner-Adair-Coppage doctrine,[157]
lost its potency as an obstacle to the enforcement of legislation
calculated to enhance the bargaining capacity of workers as against that
already possessed by their employers. Prior to the manifestation, in
Senn _v._ Tile Layers Protective Union,[158] decided in 1937, of a
greater willingness to defer to legislative judgment as to the wisdom
and need of such enactments, the Court had, on occasion, sustained
measures such as one requiring every corporation to furnish, upon
request, to any employee, when discharged or leaving its service, a
letter, signed by the superintendent or manager, setting forth the
nature and duration of his service to the corporation and stating truly
the cause of his leaving.[159] Added provisions that such letters shall
be on plain paper selected by the employee, signed in ink and sealed,
and free from superfluous figures, and words, were also sustained as not
amounting to any unconstitutional deprivation of liberty and
property.[160] On the ground that the right to strike is not absolute,
the Court in a similar manner upheld a statute by the terms of which an
officer of a labor union was punished for having ordered a strike for
the purpose of enforcing a payment to a former employee of a stale claim
for wages.[161]

The significance of the case of Senn _v._ Tile Layers Protective
Union[162] as an indicator of the range of the alteration of the Court's
views concerning the constitutionality of State labor legislation
derives in part from the fact that the statute upheld therein was not
appreciably different from that voided in Truax _v._ Corrigan.[163] Both
statutes were alike in that they withheld the remedy of injunction; but
by reason of the fact that the invalidated act did not contain the more
liberal and also more precise definition of a labor dispute set forth in
the later enactment and, above all, did not affirmatively purport to
sanction peaceful picketing only, the Court was enabled to maintain that
Truax _v._ Corrigan, insofar as "the statute there in question was * * *
applied to legalize conduct which was not simply peaceful picketing,"
was distinguishable. Specifically, the Court in the Senn Case gave its
approval to the application o