should not escape with impunity,"[66] has in all cases overborne all the common juridical rules of evidence,—­it has even prevailed over the first and most natural construction of acts of Parliament, and that in matters of so penal a nature as high treason.  It is known that statutes made, not to open and enlarge, but on fair grounds to straiten proofs, require two witnesses in cases of high treason.  So it was understood, without dispute and without distinction, until the argument of a case in the High Court of Justice, during the Usurpation.  It was the case of the Presbyterian minister, Love, tried for high treason against the Commonwealth, in an attempt to restore the King.  In this trial, it was contended for, and admitted, that one witness to one overt act, and one to another overt act of the same treason, ought to be deemed sufficient.[67] That precedent, though furnished in times from which precedents were cautiously drawn, was received as authority throughout the whole reign of Charles II.; it was equally followed after the Revolution; and at this day it is undoubted law.  It is not so from the natural or technical rules of construction of the act of Parliament, but from the principles of juridical policy.  All the judges who have ruled it, all the writers of credit who have written upon it, assign this reason, and this only,—­that treasons, being plotted in secrecy, could in few cases be otherwise brought to punishment.

The same principle of policy has dictated a principle of relaxation with regard to severe rules of evidence, in all cases similar, though of a lower order in the scale of criminality.  It is against fundamental maxims that an accomplice should be admitted as a witness:  but accomplices are admitted from the policy of justice, otherwise confederacies of crime could not be dissolved.  There is no rule more solid than that a man shall not entitle himself to profit by his own testimony.  But an informer, in case of highway robbery, may obtain forty pounds to his own profit by his own evidence:  this is not in consequence of positive provision in the act of Parliament; it is a provision of policy, lest the purpose of the act should be defeated.

Now, if policy has dictated this very large construction of an act of Parliament concerning high treason, if the same policy has dictated exceptions to the clearest and broadest rules of evidence in other highly penal causes, and if all this latitude is taken concerning matters for the greater part within our insular bounds, your Committee could not, with safety to the larger and more remedial justice of the Law of Parliament, admit any rules or pretended rules, unconnected and uncontrolled by circumstances, to prevail in a trial which regarded offences of a nature as difficult of detection, and committed far from the sphere of the ordinary practice of our courts.