2 U.S.C. § 291: Congressional declaration of purpose

in accordance with the principle of equal pay for substantially equal work, and with due regard to (i) differences in the levels of difficulty, responsibility, and qualification requirements of the work, (ii) the kind of work performed, (iii) satisfactory performance, and (iv) length of service; the application of appropriate position standards and position descriptions for such positions; and the adoption of organization and position titles in the House which accurately reflect the respective functions, duties, and responsibilities of those organizations and positions in the House to which this chapter applies. Notwithstanding any provision of this Act [this chapter], the aggregate (gross) rate of compensation of any employee immediately prior to the effective date of this Act [ Jan. 1, 1965 ] shall not be reduced by reason of the enactment of this Act. is receiving basic compensation from more than one civilian office or position and is in compliance with such law