United States person
The term United States person or U.S. person is used in various contexts in U.S. laws and regulations with different meanings.
Data collection and intelligence
The term "U.S. person" is used in the context of data collection and intelligence by the United States, particularly with respect to the provisions of the Foreign Intelligence Surveillance Act. If information from, about, or to a U.S. person who is not a named terrorist is captured in the course of U.S. foreign intelligence activities, there are strict rules about preserving the anonymity of such a person in any subsequent intelligence report. Only if the U.S. person information is relevant to the report, is it included.
- a citizen of the United States
- an alien lawfully admitted for permanent residence
- an unincorporated association with a substantial number of members who are citizens of the U.S. or are aliens lawfully admitted for permanent residence
- a corporation that is incorporated in the U.S.
Securities market regulation
- Any natural person resident in the United States;
- Any partnership or corporation organized or incorporated under the laws of the United States;
- Any estate of which any executor or administrator is a U.S. person;
- Any trust of which any trustee is a U.S. person;
- Any agency or branch of a foreign entity located in the United States;
- Any non-discretionary account or similar account (other than an estate or trust) held by a dealer or other fiduciary for the benefit or account of a U.S. person;
- Any discretionary account or similar account (other than an estate or trust) held by a dealer or other fiduciary organized, incorporated, or (if an individual) resident in the United States; and
- Any partnership or corporation if:
- Organized or incorporated under the laws of any foreign jurisdiction; and
- Formed by a U.S. person principally for the purpose of investing in securities not registered under the Act, unless it is organized or incorporated, and owned, by accredited investors (as defined in Rule 501(a)) who are not natural persons, estates or trusts.
Section 902(k)(2) further defines some persons who are explicitly not U.S. persons. Unlike other definitions of U.S. person, the Regulation S definition of U.S. person does not include U.S. citizens not resident in the U.S.
- a citizen or resident of the United States,
- a domestic partnership,
- a domestic corporation,
- any estate (other than a foreign estate, within the meaning of paragraph (31)), and
- any trust if—
- a court within the United States is able to exercise primary supervision over the administration of the trust, and
- one or more United States persons have the authority to control all substantial decisions of the trust.
- Holders of US residence visa "Green Card" (until cancelled with the Internal Revenue Service) 
- NSA SIGINT FAQ
- General Rules and Regulations promulgated under the Securities Act of 1933: Rule 902 -- Definitions
- TITLE 26 > Subtitle F > CHAPTER 79 > § 7701. DEFINITIONS
- "If you have a U.S. green card, you are a lawful permanent resident of the U.S. even if you live abroad. This means you are treated as a U.S. resident for U.S. income tax purposes and you are subject to U.S. tax on your worldwide income from whatever source derived. Accoridingly, you must fie a U.S. tax return unless there has been a final administrative or judicial determination that your lawful permanent resident status has been revoked or abandoned, your gross income from wordwide sources less than the amounts that require a tax return to be filed, or your U.S. residence status is affected by an income tax treaty... http://photos.state.gov/libraries/hamilton/19452/pdfs/greencardholdertaxguide.pdf