James Moore Wayne,
Brown v. Swann (35 U.S. 497) — Opinion of the Court
“ In other words, it is a bill to discover facts, which cannot be proved, according to the existing forms of procedure at law. The jurisdiction of a court of equity, in this regard, rests upon the inability of the courts of common law to obtain, or to compel such testimony to be given. It has no other foundation: and whenever a discovery of this kind is sought in equity, if it shall appear that the same facts could be obtained by the process of the courts of common law, it is an abuse of the powers of chancery to interfere. ”
