Skidmore v. Swift & Co.
, 323 U.S. 134 (1944) is a United States Supreme Court
decision that stands for the proposition that an administrative agency's interpretive rules will be given deference according to their persuasiveness. The four-factor test looks at: (1) the thoroughness of the agency's investigation; (2) the validity of its reasoning; (3) the consistency of its interpretation over time; and (4) other persuasive powers of the agency.
The continuing vitality of Skidmore deference is in question. Justice Scalia, in his dissent in Christensen v. Harris County, argued that Skidmore has no place post-Chevron. However, the majority in Christensen held that an agency's interpretation of a statute announced in more informal agency papers (such as an opinion letter) is entitled to Skidmore deference, not Chevron deference.