Armed Career Criminal Act
The Armed Career Criminal Act of 1984 (ACCA) is a United States federal law that provides sentence enhancements for felons who commit crimes with firearms, if convicted of certain crimes three or more times.
If a felon has been convicted more than twice of a "violent felony" or a "serious" drug crime, the Act provides a minimum sentence of fifteen years, instead of the ten-year maximum prescribed under the Gun Control Act. The Act provides for a maximum sentence of life imprisonment.
History of ACCA
The ACCA has been through numerous revisions in Congress and has evolved considerably since its passage in 1984.
The ACCA was originally included with the Comprehensive Crime Control Act of 1984 sponsored by the Reagan Administration and enhanced the penalties for possession of firearms under the Gun Control Act for felons who had been convicted three times of robbery or burglary.
On June 26, 2015, the Supreme Court of the United States ruled that the ACCA residual clause is unconstitutional.  The Courth thus struck down a "catchall phrase" in the ACCA that was described as "vague" in outlining acts that could result in a harsher sentence.
Cases involving the ACCA
The definition of "violent felony" in ACCA has recently been interpreted by the United States Supreme Court in Begay v. United States and in Chambers v. United States. The definition of "violent felony" has also been called into question by the Supreme Court in Johnson v. United States, which will be heard for the second time in the spring of 2015.
The definition of a "serious" drug crime was considered and further defined by the Supreme Court in United States v. Rodriquez. In Taylor v. United States, the Court was called upon to determine the meaning of the word "burglary" in ACCA and, specifically, whether a conviction in Missouri for second-degree burglary was, in fact, a predicate conviction. The court concluded that an offense constitutes "burglary" under 924(e) if, regardless of its exact definition or label, it has the basic elements of burglary.
"Under the Armed Career Criminal Act of 1984, a defendant convicted of being a felon in possession of a firearm faces more severe punishment if he has three or more previous convictions for a 'violent felony,' a term defined to include any felony that 'involves conduct that presents a serious potential risk of physical injury to another.' 18 U. S. C. §924(e)(2)(B). We must decide whether this part of the definition of a violent felony survives the Constitution’s prohibition of vague criminal laws. "
"We hold that imposing an increased sentence under the residual clause of the Armed Career Criminal Act violates the Constitution’s guarantee of due process. Our contrary holdings in James and Sykes are overruled. Today’s decision does not call into question application of the Act to the four enumerated offenses, or the remainder of the Act’s definition of a violent felony." 
- 18 U.S.C. § 924(e)
- These prior convictions are referred to as "predicate" convictions, i.e. the Government must prove the existence of three prior convictions as a "predicate" for the imposition of the sentence enhancement under ACCA.
- For an analysis of the ACCA's legislative history and proposals for amending the ACCA, consult this 2009 article from the Harvard Journal on Legislation: The Armed Career Criminal Act and the U.S. Sentencing Guidelines: Moving Toward Consistency, 46 Harv. J. on Legis. 537 (2009)
- When H.R. 6248 was passed by Congress and presented to Reagan for signature, he vetoed the bill on the ground that identical provisions had been enacted a week earlier as part of P.L. 98-473. Reagan Veto Memorandum.
- The original ACCA was codified at 18 U.S.C. 1202(a).
- 18 U.S.C. 924(e)(2)(B)
- Chambers at LII