In the year 1715 (1 Geo. I.) the Commons thought proper to impeach of high treason the lords who had entered into the rebellion of that period.  This was about six years after the decision in the case of Sacheverell.  On the trial of one of these lords, (the Lord Wintoun,[13]) after verdict, the prisoner moved in arrest of judgment, and excepted against the impeachment for error, on account of the treason therein laid “not being described with sufficient certainty,—­the day on which the treason was committed not having been alleged.”  His counsel was heard to this point.  They contended, “that the forfeitures in cases of treason are very great, and therefore they humbly conceived that the accusation ought to contain all the certainty it is capable of, that the prisoner may not by general allegations be rendered incapable to defend himself in a case which may prove fatal to him:  that they would not trouble their Lordships with citing authorities; for they believed there is not one gentleman of the long robe but will agree that an indictment for any capital offence to be erroneous, if the offence be not alleged to be committed on a certain day:  that this impeachment set forth only that in or about the months of September, October, or November, 1715, the offence charged in the impeachment had been committed.”  The counsel argued, “that a proceeding by impeachment is a proceeding at the Common Law, for Lex Parliamentaria is a part of Common Law, and they submitted whether there is not the same certainty required in one method of proceeding at Common Law as in another.”

The matter was argued elaborately and learnedly, not only on the general principles of the proceedings below, but on the inconvenience and possible hardships attending this uncertainty.  They quoted Sacheverell’s case, in whose impeachment “the precise days were laid when the Doctor preached each of these two sermons; and that by a like reason a certain day ought to be laid in the impeachment when this treason was committed; and that the authority of Dr. Sacheverell’s case seemed so much stronger than the case in question as the crime of treason is higher than that of a misdemeanor.”

Here the Managers for the Commons brought the point a second time to an issue, and that on the highest of capital cases:  an issue, the event of which was to determine forever whether their impeachments were to be regulated by the law as understood and observed in the inferior courts.  Upon the usage below there was no doubt; the indictment would unquestionably have been quashed.  But the Managers for the Commons stood forth upon this occasion with a determined resolution, and no less than four of them seriatim rejected the doctrine contended for by Lord Wintoun’s counsel.  They were all eminent members of Parliament, and three of them great and eminent lawyers, namely, the then Attorney-General, Sir William Thomson, and Mr. Cowper.