The president of my university posed that question in her Constitution Day (we actually have such a thing, it's September 17) blog in 2013 and asked students and faculty to respond. The most recent mass shooting at that time was at the Washington Navy Yard. My response is below. As President Obama noted: nothing ever seems to change on this topic.
Prior to the Supreme Court’s 5-4 decisions in Heller v. District of Columbia, 554 U.S. 570 (2008) and McDonald v. Chicago, 561 U.S. 3025 (2010), there would have been no legal (as opposed to policy) dispute (as to whether the 2nd Amendment prohibited effective gun control laws). The law was clear and unambiguous. In the last 2nd Amendment case before the Supreme Court prior to Heller, United States v. Miller, 307 U.S. 174 (1939) a unanimous Supreme Court ruled that the National Firearms Act did not violate the 2nd Amendment, stating:
"In the absence of any evidence tending to show that possession or use of a “shotgun having a barrel of less than eighteen inches in length” at this time has some reasonable relationship to the preservation or efficiency of a well regulated militia, we cannot say that the Second Amendment guarantees the right to keep and bear such an instrument. Certainly it is not within judicial notice that this weapon is any part of the ordinary military equipment, or that its use could contribute to the common defense.”
Miller also cited similar precedent dating to the 1870’s.
The ruling in Miller and the ability of National and State governments to regulate firearms was not seriously questioned until the 1970’s, (perhaps in response to gun-control legislation passed in response to the assassinations of Robert F. Kennedy and Martin Luther King, Jr.) when a small but well-funded group of legal scholars began to assert an individual, fundamental right to bear arms (the first example of this argument in a law review came in 1974, in a note authored by law student David Hardy, whose unorthodox positions were soon echoed by 2nd Amendment absolutists like Gary Kleck and David Kopel, among others).
In 1991, former Chief Justice Warren Burger (appointed by Richard Nixon) reacted to these new 2nd Amendment arguments on the “MacNeil/Lehrer NewsHour,” saying that the Second Amendment “has been the subject of one of the greatest pieces of fraud — I repeat the word ‘fraud’ — on the American public by special interest groups that I have ever seen in my lifetime.” He was referring to the campaign by pro-gun organizations since the 1970’s to create an interpretation of the 2nd Amendment as a fundamental right that could not be subject to regulation by the federal government or the states. In contemporaneous articles, Burger also addressed the meaning of “a well-regulated militia” and the history of gun ownership and regulation in American society from colonial times until the 20th century in support reasonable firearms regulation. With the Heller and McDonald decisions, however, Chief Justice Burger’s “fraud” has now become the law and the McDonald decision seems to allow very little room to regulate beyond prohibitions against sawed-off shotguns, or possession by felons and the mentally ill.
“Does the Constitution stand in the way of effective gun regulation in the country?" The answer is that the Constitution, by any fair reading, does not but the current Supreme Court, by ignoring decades-old precedent, does. That said, it is also time to seriously question whether this Supreme Court, with its willingness to ignore settled law and create unique interpretations of the Constitution by the slimmest 5-4 majorities, is closer to losing its legitimacy than at any time since “the switch in time that saved nine.”