An act of Congress which prescribed as a qualification for practice
before the federal courts an oath that the attorney had not participated
in the Rebellion was found unconstitutional since it operated as a
punishment for past acts.[1477] But a statute which denied to
polygamists the right to vote in a territorial election, was upheld even
as applied to a person who had not practiced polygamy since the act was
passed, because the law did not operate as an additional penalty for the
offense of polygamy but merely defined it as a disqualification of a
voter.[1478] A deportation law authorizing the Secretary of Labor to
expel aliens for criminal acts committed before its passage is not _ex
post facto_ since deportation is not a punishment.[1479] Likewise an act
permitting the cancellation of naturalization certificates obtained by
fraud prior to the passage of the law was held not to impose a
punishment but simply to deprive the alien of his ill-gotten
privileges.[1480]

Change in Place or Mode of Trial

A change of the place of trial of an alleged offense after its
commission, is not an _ex post facto_ law. If no place of trial was
provided when the offense was committed, Congress may designate the
place of trial thereafter.[1481] A law which alters the rule of evidence
to permit a person to be convicted upon less or different evidence than
was required when the offense was committed is invalid,[1482] but a
statute which simply enlarges the class of persons who may be competent
to testify in criminal cases is not _ex post facto_ as applied to a
prosecution for a crime committed prior to its passage.[1483]

Clause 4. No Capitation, or other direct, Tax shall be laid, unless in
Proportion to the Census or Enumeration herein before directed to be
taken.

DIRECT TAXES

The Hylton Case

The crucial problem under this section is to distinguish "direct" from
other taxes. In its opinion in Pollock _v._ Farmers' Loan and Trust
Co., we find the Court declaring: "It is apparent * * * that the
distinction between direct and indirect taxation was well understood by
the framers of the Constitution and those who adopted it."[1484] Against
this confident dictum may be set the following brief excerpt from
Madison's Notes on the Convention: "Mr. King asked what was the precise
meaning of _direct_ taxation? No one answered."[1485] The first case to
come before the Court on this issue was Hylton _v._ United States,[1486]