Yes Miller had died before the case reached SCOTUS and his attorney didn’t bother to travel to DC. The governments case was left unchallenged.
The FDR administration was looking for a test case to take to the Supreme Court, establishing federal regulation of firearms commerce as “constitutional.” Two months before the passage of the 1938 NFA, on 18 April 1938, two small-time criminals were arrested for “making preparation for armed robbery”, by Oklahoma and Arkansas state police. They had in their possession a short-barreled shotgun. They had traveled from Oklahoma to Arkansas. They were brought to Fort Smith, Arkansas.
One of them, Jackson “Jack” Miller, had been an informant and participant in a significant case involving the O’Malley gang. He was known to the U.S. Attorney for the Western District of Arkansas, Clinton R. Barry. Barry saw an opportunity for an NFA of 1934 test case. He wired the United States Attorney General on 23 April 1938, explaining the importance of acting quickly before the pair were released on bail.
Miller was also known to the federal judge who had presided over the O’Malley case, Heartsill Ragon. Judge Heartsill Ragon was the 1930s version of Chuck Schumer, a strong proponent of restrictive federal gun law. He helped push through the New Deal for FDR before being rewarded with a federal judgeship in Arkansas.
The NFA case was given to Judge Heartsill Ragon. He appointed the defense counsel. He refused to accept a guilty plea.
Judge Ragon had the case he wanted, the defendants he wanted, and the defense council he wanted. Judge Ragon then created the only defense for the case, it was his memorandum opinion.
On June 11, 1938 Miller and Layton demurred to the indictment, claiming that it presented insufficient evidence of a transfer requiring payment of a tax and challenging the constitutionality of the NFA under the Second and Tenth Amendments. Surprisingly, Ragon immediately issued a memorandum opinion sustaining the demurrer and quashing the indictment. He held that the NFA violates the Second Amendment by prohibiting the transportation of unregistered covered firearms in interstate commerce.
This position was diametrically opposite to his stated opinion while a legislator. It did not include any facts or analysis to support the proposition.
The FDR administration appealed the case directly to the Supreme Court. With only the government’s side of the case presented, the Court refused to strike down the law. The Miller decision was muddy and subject to interpretation.