As teamorion22 said, the US Supreme Court struck down the District of Columbia's ban on handgun possession in the home, and the requirement that firearms in the home be disassembled or bound by a trigger lock. Essentially, this sends a message to other states that similar bans will also be struck down as unconstitutional. Justice SCALIA wrote the Opinion, and Chief Justice ROBERTS, and Justices KENNEDY, THOMAS, and ALITO, joined in the Opinion. Justices STEVENS, SOUTER, GINSBURG, and BREYER dissented (that is, disagreed).
Senators and Representatives (state or national) can vote for and against all the laws they want, but if they pass a law that's unconstitutional (as decided by the courts), then the law goes ... well ... "bye-bye."
You can read the Opinion here; note that the "Syllabus" is not the Opinion of the Court, but a synopsis prepared by the reporter:
http://www.supremecourtus.gov/opinions/07pdf/07-290.pdf
Here's part of the Syllabus:
District of Columbia law bans handgun possession by making it a crime to carry an unregistered firearm and prohibiting the registration of handguns; provides separately that no person may carry an unlicensed handgun, but authorizes the police chief to issue 1-year licenses; and requires residents to keep lawfully owned firearms unloaded and disassembled or bound by a trigger lock or similar device. Respondent Heller, a D. C. special policeman, applied to register a handgun he wished to keep at home, but the District refused.
He filed this suit seeking, on Second Amendment grounds, to enjoin the city from enforcing the bar on handgun registration, the licensing
requirement insofar as it prohibits carrying an unlicensed firearm in the home, and the trigger-lock requirement insofar as it prohibits the
use of functional firearms in the home. The District Court dismissed the suit, but the D. C. Circuit reversed, holding that the Second
Amendment protects an individual’s right to possess firearms and that the city’s total ban on handguns, as well as its requirement that
firearms in the home be kept nonfunctional even when necessary for self-defense, violated that right.
Held:
1. The Second Amendment protects an individual right to possess a firearm unconnected with service in a militia, and to use that arm for traditionally lawful purposes, such as self-defense within the home. ...
* * *
2. Like most rights, the Second Amendment right is not unlimited. It is not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose: For example, concealed weapons prohibitions have been upheld under the Amendment or state analogues. The Court’s opinion should not be taken to cast doubt on longstanding prohibitions on the possession of firearms by felons and the mentally ill, or laws forbidding the carrying of firearms in sensitive places such as schools and government buildings, or laws imposing conditions and qualifications on the commercial sale of arms. Miller’s holding that the sorts of weapons protected are those
“in common use at the time” finds support in the historical tradition of prohibiting the carrying of dangerous and unusual weapons. ...
3. The handgun ban and the trigger-lock requirement (as applied to self-defense) violate the Second Amendment. The District’s total ban on handgun possession in the home amounts to a prohibition on an entire class of “arms” that Americans overwhelmingly choose for the lawful purpose of self-defense. Under any of the standards of scrutiny the Court has applied to enumerated constitutional rights, this prohibition—in the place where the importance of the lawful defense of self, family, and property is most acute—would fail constitutional muster. Similarly, the requirement that any lawful firearm in the home be disassembled or bound by a trigger lock makes it impossible for citizens to use arms for the core lawful purpose of self-defense and is hence unconstitutional. Because Heller conceded at oral argument that the D. C. licensing law is permissible if it is not enforced arbitrarily and capriciously, the Court assumes that a license will satisfy his prayer for relief and does not address the licensing requirement. Assuming he is not disqualified from exercising Second Amendment rights, the District must permit Heller to register his handgun and must issue him a license to carry it in the home. ....