State law, had sold milk to the United States for consumption by troops
at an army camp located on land belonging to the State, at prices below
the minima established by the Commission.[25] The majority was unable to
find in Congressional legislation, or in the Constitution, unaided by
Congressional enactment, any immunity from such price-fixing
regulations. On the same day, a different majority held that California
could not penalize a milk dealer for selling milk to the War Department
at less than the minimum price fixed by State law where the sales and
deliveries were made in a territory which had been ceded to the Federal
Government by the State and were subject to the exclusive jurisdiction
of the former.[26]

OBLIGATION OF STATE COURTS UNDER THE SUPREMACY CLAUSE

The Constitution, laws and treaties of the United States are as much a
part of the law of every State as its own local laws and Constitution.
Their obligation "is imperative upon the State judges, in their official
and not merely in their private capacities. From the very nature of
their judicial duties, they would be called upon to pronounce the law
applicable to the case in judgment. They were not to decide merely
according to the laws or Constitution of the State, but according to the
laws and treaties of the United States--'the supreme law of the
land.'"[27] State courts have both the power and the duty to enforce
obligations arising under federal law, unless Congress gives the federal
courts exclusive jurisdiction. The power of State courts to entertain
such suits was affirmed in Claflin _v._ Houseman[28] in 1876, thus
setting at rest the doubts which had been raised by an early dictum of
Justice Story.[29] In the Claflin case Justice Bradley asserted on
behalf of a unanimous court that: "If an Act of Congress gives a penalty
to a party aggrieved, without specifying a remedy for its enforcement,
there is no reason why it should not be enforced, if not provided
otherwise by some act of Congress, by a proper action in a State court.
The fact that a State court derives its existence and functions from the
State laws is no reason why it should not afford relief, because it is
subject also to the laws of the United States, and is just as much bound
to recognize these as operative within the State as it is to recognize
the State laws."[30] When the Supreme Court of Connecticut held that
rights created by the Federal Employer's Liability Acts could not be