“ This resulted in a judgment for the defendants, and when the case came here this court pronounced the trial court's theory untenable, sustained the government's right to read the deposition, and reversed the judgment, saying (p. 481) : 'A witness who proves facts entitling the plaintiff in a proceeding in a court of the United States, even if the plaintiff be the government, to a judgment for money only, and not to a judgment which directly involves the personal safety of the defendant, is not, within the meaning of the 6th Amendment, a witness against an 'accused' in a criminal prosecution ”

“ The district attorney is required to prosecute every such 'suit' when brought by the United States. These references in the statute to the proceeding for recovering the penalty plainly indicate that a civil action is an appropriate mode of proceeding. ”

“ It cannot be that whether an action of debt is maintainable or not depends upon the question who is the plaintiff. Debt lies whenever a sum certain is due to the plaintiff, or a sum which can readily be reduced to a certainty,-a sum requiring no future valuation to settle its amount. ”

“ The district court instructed the jury that this measure of proof was required, and the instruction was approved by the circuit court of appeals. 31 L.R.A. (N.S.) 1073, 105 C. C. A. 505, 183 Fed. 293, 121 C. C. A. 543, 203 Fed. 433. ”

“ And such, also, is the prevalent course of decision in the state courts. 4 Wigmore, Ev. § 2498; People v. Briggs, 114 N. Y. 56, 20 N. E. 820; State v. Chicago, M. & St. P. R. Co. 122 Iowa, 22, 101 Am. St. Rep. ”