Twelve months had hardly elapsed since the legislature had, in
very peculiar circumstances, and for very plausible reasons,
taken upon itself to try and to punish a great criminal whom it
was impossible to reach in the ordinary course of justice; and
already the breach then made in the fences which protect the
dearest rights of Englishmen was widening fast. What had last
year been defended only as a rare exception seemed now to be
regarded as the ordinary rule. Nay, the bill of pains and
penalties which now had an easy passage through the House of
Commons was infinitely more objectionable than the bill which had
been so obstinately resisted at every stage in the preceding
session.

The writ of attainder against Fenwick was not, as the vulgar
imagined and still imagine, objectionable because it was
retrospective. It is always to be remembered that retrospective
legislation is bad in principle only when it affects the
substantive law. Statutes creating new crimes or increasing the
punishment of old crimes ought in no case to be retrospective.
But statutes which merely alter the procedure, if they are in
themselves good statutes, ought to be retrospective. To take
examples from the legislation of our own time, the Act passed in
1845, for punishing the malicious destruction of works of art
with whipping, was most properly made prospective only. Whatever
indignation the authors of that Act might feel against the
ruffian who had broken the Barberini Vase, they knew that they
could not, without the most serious detriment to the
commonwealth, pass a law for scourging him. On the other hand the
Act which allowed the affirmation of a Quaker to be received in
criminal cases allowed, and most justly and reasonably, such