18 U.S.C. § 921

(32) The term ''intimate partner'' means, with respect to a person, the spouse of the person, a former spouse of the person, an individual who is a parent of a child of the person, and an individual who cohabitates or has cohabited with the person.

(33) (A) Except as provided in subparagraph (C), the term ''misdemeanor crime of domestic violence'' means an offense that

(i) is a misdemeanor under Federal or State law; and
(ii) has, as an element, the use or attempted use of physical force, or the threatened use of a deadly weapon, committed by a current or former spouse, parent, or guardian of the victim, by a person with whom the victim shares a child in common, by a person who is cohabiting with or has cohabited with the victim as a spouse, parent, or guardian, or by a person similarly situated to a spouse, parent, or guardian of the victim.

18 U.S.C. § 922 (g)

It shall be unlawful for any person

(8) who is subject to a court order that

(A) was issued after a hearing of which such person received actual notice, and at which such person had an opportunity to participate;

(B) restrains such person from harassing, stalking, or threatening an intimate partner of such person or child of such intimate partner or person, or engaging in other conduct that would place an intimate partner in reasonable fear of bodily injury to the partner or child; and

(C) (i) includes a finding that such person represents a credible threat to the physical safety of such intimate partner or child; or
(ii) by its terms explicitly prohibits the use, attempted use, or threatened use of physical force against such intimate partner or child that would reasonably be expected to cause bodily injury; or

(9) who has been convicted in any court of a misdemeanor crime of domestic violence,
to ship or transport in interstate or foreign commerce, or possess in or affecting commerce, any firearm or ammunition; or to receive any firearm or ammunition which has been shipped or transported in interstate or foreign commerce.

Read FEDERAL FULL FAITH AND CREDIT LEGISLATION.
Read INTERSTATE DOMESTIC VIOLENCE LEGISLATION.
Read INTERSTATE STALKING LEGISLATION.
Read INTERSTATE PROTECTION ORDER LEGISLATION.