Pike received a Sterling Fellowship and earned a J.S.D. from Yale Law School in 1938. After leaving Yale, he served as a staff attorney for the New Deal-era Securities and Exchange Commission in Washington, D.C. from 1938 to 1942, in addition to lecturing on federal procedure at Catholic University of America Law School (1938-1939) and in civil procedures at George Washington University Law School (1939-1942). He then established the law firm of Pike and Fischer with a fellow attorney, specializing in the publication of books on federal judicial and administrative procedure.