jeopardy.[35] Congress may impose both
criminal and civil sanctions with respect to the same act or
omission,[36] and may separate a conspiracy to commit a substantive
offense from the commission of the offense and affix to each a different
penalty.[37] A conviction for the conspiracy may be had though the
subsequent offense was not completed.[38] Separate convictions under
different counts charging a monopolization and a conspiracy to
monopolize trade, in an indictment under the Sherman Antitrust Act, do
not amount to double jeopardy.[39] In United States _v._ National
Association of Real Estate Boards,[40] the Court held that an acquittal
in a criminal suit charging violation of the Sherman Act does not
prevent the issuance of an injunction against future violations. It
distinguished but did not overrule an early case which held that where
an issue as to the existence of a fact or act had been tried in a
criminal proceeding instituted by the United States, a judgment of
acquittal, was conclusive in a subsequent proceeding _in rem_ involving
the same matter.[41]

A civil action to recover taxes which were in fact penalties for
violation of another statute was held to be punitive in character and
barred by a prior conviction of the defendant for a criminal offense
involving the same transaction.[42] In contrast, the additional income
tax imposed when a fraudulent return is filed, was found to be a civil
sanction designed to protect the revenue, which might be assessed after
acquittal of the defendant for the same fraud.[43] A forfeiture
proceeding for defrauding the Government of a tax on alcohol diverted to
beverage uses is a proceeding _in rem_, rather than a punishment for a
criminal offense, and may be prosecuted after a conviction of conspiracy
to violate the statute imposing the tax.[44]

In an early case, the Court asserted that since robbery on the high seas
is considered an offense within the criminal jurisdiction of all
nations, the plea of _autre fois acquit_ would be good in any civilized
State, though resting on a prosecution instituted in the courts of any
other civilized State.[45] It has held, however, that where the same act
is an offense against both the State and Federal Governments, its
prosecution and punishment by both Governments is not double
jeopardy.[46] A contumacious witness is not twice subjected to jeopardy
for refusing to testify before a committee of the United States Senate,
by being