A statute should be read as a whole and harmoniously.  When parts of a statute are ambiguous, it should be interpreted by the judiciary in order to give effect to the legislative intention.  Legislature’s delegate powers to administrative agencies to decide matters that need specialization and expertise.  While making a decision administrative agencies are to interpret ambiguous provisions in statutes reasonably.

When the legislature reenacts a statutory provision without making any material change it implies approval of administrative interpretation of the statute.  In Helvering v. Winmill, 305 U.S. 79 (U.S. 1938), the US Supreme Court held that interpretations made by administrative agencies that continue without any material change are deemed to have received congressional approval.  This implication is with respect to unamended provisions in a statute or substantially reenacted statutes.  The legislature also approves administrative agency’s interpretation of statutes when the interpretation is judicially approved[i].  Legislative approval is implied in administrative interpretations where there is ample evidence that legislature has considered the continued use of same interpretation by administrative agencies.[ii].

Legislature may also approve an administrative agency’s interpretation of a statute, when after the agency’s interpretation the legislature amends the statute to clarify its intention.  When congress does not revise or repeal a provision that was interpreted by an administrative agency, while amending the statute it is a persuasive evidence that congress also intended the administrative construction[iii].

[i] Connecticut Dep’t of Income Maintenance v. Heckler, 471 U.S. 524 (U.S. 1985)

[ii] NLRB v. Gullett Gin Co., 340 U.S. 361 (U.S. 1951)

[iii] Catron County Bd. of Comm’rs v. United States Fish & Wildlife Serv., 75 F.3d 1429 (10th Cir. N.M. 1996)