elves to pay money at a future day for services rendered or
money borrowed.[1551] Bills issued by State banks are not bills of
credit;[1552] it is immaterial that the State is the sole stockholder of
the bank,[1553] that the officers of the bank were elected by the State
legislature,[1554] or that the capital of the bank was raised by the
sale of State bonds.[1555]

LEGAL TENDER

Relying on this clause, which applies only to the States and not to the
Federal Government,[1556] the Supreme Court has held that where the
marshal of a State court received State bank notes in payment and
discharge of an execution, the creditor was entitled to demand payment
in gold or silver.[1557] Since, however, there is nothing in the
Constitution which prohibits a bank depositor from consenting when he
draws a check, that payment may be made by draft, a State law which
provided that checks drawn on local banks should, at the option of the
bank, be payable in exchange drafts was held valid.[1558]

BILLS OF ATTAINDER

Statutes passed after the Civil War with the intent and result of
excluding persons who had aided the Confederacy from following certain
callings, by the device of requiring them to take an oath that they had
never given such aid, were held invalid as being bills of attainder, as
well as _ex post facto_ laws.[1559]

EX POST FACTO LAWS

Scope of Provision

This clause, like the cognate restriction imposed on the Federal
Government by section 9, relates only to penal and criminal legislation
and not to civil laws which affect private rights adversely.[1560] It is
directed only against legislative action and does not touch erroneous or
inconsistent decisions by the courts.[1561] Even though a law is _ex
post facto_ and invalid as to crimes committed prior to its enactment,
it is nonetheless valid as to subsequent offenses.[1562] If it mitigates
the rigor of the law in force at the time the crime was committed,[1563]
or if it merely penalizes the continuance of conduct which was lawfully
begun before its passage, the statute is not _ex post facto_. Thus
measures penalizing the failure of a railroad to cut drains through
existing embankments,[1564] or making illegal the continued possession
of intoxicating liquors which were lawfully acquired,[1565] have been
held valid.

Denial of Future Privileges to Past Offenders

The right to practice a profession may be denied to one who was
convicted of an offense befor