Article I, Section 9, Clause 3:
No Bill of Attainder or ex post facto Law shall be passed.
The issue of whether a law is civil or punitive in nature is essentially the same for ex post facto and for double jeopardy analysis. 1
A court must ascertain whether the legislature intended the statute to establish civil proceedings. A court will reject the legislature’s manifest intent only where a party challenging the Act provides the clearest proof that the statutory scheme is so punitive in either purpose or effect as to negate the State’s intention. 2 A statute that has been held to be civil and not criminal in nature cannot be deemed punitive
as applied to a single individual. 3
A variety of federal laws have been challenged as ex post facto. A statute that prescribed as a qualification for practice before the federal courts an oath that the attorney had not participated in the Rebellion was found unconstitutional because it operated as a punishment for past acts. 4 But a statute that denied to polygamists the right to vote in a territorial election was upheld even as applied to one who had not contracted a polygamous marriage and had not cohabited with more than one woman 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. 5 A deportation law authorizing the Secretary of Labor to expel aliens for criminal acts committed before its passage is not ex post facto because deportation is not a punishment. 6 For this reason, a statute terminating payment of old-age benefits to an alien deported for Communist affiliation also is not ex post facto, for the denial of a non-contractual benefit to a deported alien is not a penalty but a regulation designed to relieve the Social Security System of administrative problems of supervision and enforcement likely to arise from disbursements to beneficiaries residing abroad. 7 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 instead simply to deprive the alien of his ill-gotten privileges. 8