Cowman, you know so much about the Second Amendment

I trust you are familiar with US v. Miller, 307 U.S. 174 (1939).

At the end of the decision it says:

MR. JUSTICE DOUGLAS took no part in the consideration or decision of this cause.

That refers to Justice WIlliam O. Douglas who had just joined the court at the time the decision had argued. In a later case, Adams v. Williams, 407 U.S 143(1972) Justice Douglas said at 150 -51:

The police problem is an acute one not because of the Fourth Amendment, but because of the ease with which anyone can acquire a pistol. A powerful lobby dins into the ears of our citizenry that these gun purchases are constitutional rights protected by the Second Amendment, which reads, "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."

There is under our decisions no reason why stiff state laws governing the purchase and possession of pistols may not be enacted. There is no reason why pistols may not be barred from anyone with a police record. There is no reason why a State may not require a purchaser of a pistol to pass a psychiatric test. There is no reason why all pistols should not be barred to everyone except the police.

The leading case is United States v. Miller, 307 U.S. 174, upholding a federal law making criminal the shipment in interstate commerce of a sawed-off shotgun. The law was upheld, there being no evidence that a sawed-off shotgun had "some reasonable relationship to the preservation or efficiency of a well regulated militia." Id. at 178. The Second Amendment, it was held, "must be interpreted and applied" with the view of maintaining a "militia."

The Militia which the States were expected to maintain and train is set in contrast with Troops which they were forbidden to keep without the consent of Congress. The sentiment of the time strongly disfavored standing armies; the common view was that adequate defense of country and laws could be [p151] secured through the Militia -- civilians primarily, soldiers on occasion.

Id. at 178-179.

Critics say that proposals like this water down the Second Amendment. Our decisions belie that argument, for the Second Amendment, as noted, was designed to keep alive the militia. But if watering-down is the mood of the day, I would prefer to water down the Second rather than the Fourth Amendment.

Please state why the is the longest-serving justice in the history of the Supreme Court With a term lasting 36 years and 209 days who happened to be a member of the Miller Court would not have a better understanding of US v. Miller than you do?