2 U.S. Code § 288b - Requirements for authorizing representation activity
(a) Direction of Joint Leadership Group or Senate resolution
The Counsel shall defend the Senate or a committee, subcommittee, Member, officer, or employee of the Senate under section 288c of this title only when directed to do so by two-thirds of the Members of the Joint Leadership Group or by the adoption of a resolution by the Senate.
(b) Civil action to enforce subpena
The Counsel shall bring a civil action to enforce a subpena of the Senate or a committee or subcommittee of the Senate under section 288d of this title only when directed to do so by the adoption of a resolution by the Senate.
(c) Intervention or appearance
The Counsel shall intervene or appear as amicus curiae under section 288e of this title only when directed to do so by a resolution adopted by the Senate when such intervention or appearance is to be made in the name of the Senate or in the name of an officer, committee, subcommittee, or chairman of a committee or subcommittee of the Senate.
(d) Immunity proceedings
The Counsel shall serve as the duly authorized representative in obtaining an order granting immunity under section 288f of this title of—
(1) the Senate when directed to do so by an affirmative vote of a majority of the Members present of the Senate; or