Regan v. Taxation with Representation of Washington, 461 U.S. 540 (1983), was a case in which the United States Supreme Court upheld lobbying restrictions imposed on tax-exempt non-profit corporations.

[1] The case involved several provisions of the Internal Revenue Code of 1954: Taxation with Representation of Washington (TWR), a non-profit corporation organized to promote certain interests in the field of federal taxation, was formed to take over the operation of two other nonprofit organizations, one of which had tax-exempt status under § 501(c)(3) and the other under § 501(c)(4), applied for tax-exempt status under § 501(c)(3).

The Internal Revenue Service denied the application under § 501(c)(3), because it appeared that a substantial part of the corporation's activities would consist of attempting to influence legislation, which is not permitted by § 501(c)(3).

TWR challenged the prohibition against substantial lobbying as violative of the First Amendment and the equal protection component of the Fifth Amendment's due process clause, and sought declaratory judgment that it qualified for the exemption granted by § 501(c)(3), claiming that § 501(c)(3)'s prohibition against substantial lobbying is unconstitutional under the First Amendment by imposing an "unconstitutional burden" on the receipt of tax-deductible contributions, and is also unconstitutional under the equal protection component of the Fifth Amendment's Due Process Clause because the Code permits taxpayers to deduct contributions to veterans' organizations that qualify for tax exemption under § 501(c)(19).

[5] The Commissioner of Internal Revenue, the Secretary of the Treasury and the United States, challenged the decision of the D.C.