654 LAWS OF MARYLAND. [CH. 310

No person shall be excused from attending and testify-
ing or from producing documentary evidence before the
Commission or in obedience to the subpoena of the commis-
sion, or as otherwise herein provided, on the ground of
or for the reason that the testimony or evidence, docu-
mentary or otherwise, required of him may tend to incrimi-
nate him or subject him to a penalty or forfeiture. But no
natural person shall be prosecuted or subjected to any
penalty or forfeiture for or on account of any transaction,
matter, or thing concerning which he may testify or pro-
duce evidence documentary or otherwise, before the Com-
mission in obedience to a subpoena issued by it. Provided,
that no natural person so testifying shall be exempt from
prosecution and punishment for perjury committed in so
testifying.

Section 18. It is hereby declared to be the legislative
intent that the instant, whenever that may be, that the
handling within the State by a milk dealer of milk pro-
duced outside of the State becomes a subject of regulation
by the State in the exercise of its police powers, the re-
strictions set forth in this Act respecting such milk so
produced shall apply and the powers conferred by this
Act on the commission shall attach. After any such milk
so produced shall have come to rest within the State, it
shall be subject to the provisions of this Act and the law-
ful rules and regulations of the Commission adopted pur-
suant thereto.

Section 19. No provision of this Act shall apply or be
presumed to apply to foreign or interstate commerce, ex-
cept insofar as the same may be permitted by the Constitu-
tion of the United States, the acts of Congress and treaties
made thereunder. The Commission, however, is vested with
power to confer and cooperate with the legally constituted
authorities of other states the District of Columbia and the
United States, including the Secretary of Agriculture of the
United States, in order to secure a uniform system of milk
control, and shall have power to conduct joint hearings and
issue joint or concurrent orders and to enter into compacts
for the foregoing purposes, and may exercise its powers
under this Act to effect such uniform milk control.

Section 20. The licenses and permits and other require-
ments of this Act shall be in addition to any other require-
ments, whether in the form of permits or licenses or not,
now or hereafter exacted from or imposed upon milk pro-