It may not be on the order of Brown v. Board of Education or Roe v. Wade, but Thursday’s U.S. Supreme Court ruling overturning the District of Columbia’s handgun ban will have a widespread and dramatic effect on government’s role regulating gun ownership and use. The full ramifications of the ruling will be determined later in courtrooms across the nation, but it is not hyperbole to say the court’s 5-4 decision recasts constitutional understanding of individual rights on gun ownership.

In a nutshell, the court ruled that the Second Amendment prohibits the government from enacting a blanket ban on gun ownership, as was done in Washington, D.C. The Second Amendment states: “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.” For the first 100 years or more, the amendment was generally understood to relate to state militias in their role as a bulwark against federal tyranny. But for most of the 20th century, the Second Amendment was cited as protecting the individual’s right to gun ownership. The court, for the first time, supported that view Thursday.

At the heart of the ruling is the court’s view that handguns are the American tool of choice for self-defense. Justice Antonin Scalia, who voted with the majority, said the handgun was preferred because “it can be pointed at a burglar with one hand while the other hand dials the police.” Justice Scalia tempered that view by stating the ruling should not “cast doubt on long-standing prohibitions on the possession of firearms by felons of the mentally ill, or laws forbidding the carrying of firearms in sensitive places such as schools and government buildings.”

As a general reaction, the court’s opposition to the overly broad nature of the District of Columbia’s handgun ban makes sense. But despite Justice Scalia’s caveats to the contrary, the ruling will likely open the door to legal challenges to gun restrictions across the country.

Explaining his dissenting vote, Justice John Paul Stevens wrote that the court majority is mistaken in believing “the Framers made a choice to limit the tools available to elected officials wishing to regulate civilian uses of weapons.” The First Amendment states that “Congress shall make no law … abridging the freedom of speech, or of the press …” This is not understood to mean government cannot make it illegal for people to make bomb threats or to stop newspapers from labeling people child molesters without foundation. Government retains these “tools,” Justice Stevens wrote, even when it comes to restricting guns.

If the ruling establishes as precedent the individual’s constitutional right to gun ownership – as some legal scholars suggest it does – then the burden of proof on guns shifts dramatically. Instead of groups and individuals having to make the case for their need to carry a concealed handgun or to own an assault weapon, the government must show why it needs to limit or control such gun ownership or use. It is a significant shift in the legal climate.

This ruling will loom large when the Bush legacy is considered, since the president appointed two of the five justices voting in the majority.