From the introduction to Statutory Interpretation: Theories, Tools, and Trends (R45153, Apr. 5, 2018):
The two main theories of statutory interpretation — purposivism and textualism — disagree about how judges can best adhere to this ideal of legislative supremacy. The problem is especially acute in instances where it is unlikely that Congress anticipated and legislated for the specific circumstances being disputed before the court. While purposivists argue that courts should prioritize interpretations that advance the statute’s purpose, textualists maintain that a judge’s focus should be confined primarily to the statute’s text.
Regardless of their interpretive theory, judges use many of the same tools to gather evidence of statutory meaning. First, judges often begin by looking to the ordinary meaning of the statutory text. Second, courts interpret specific provisions by looking to the broader statutory context. Third, judges may turn to the canons of construction, which are presumptions about how courts ordinarily read statutes. Fourth, courts may look to the legislative history of a provision. Finally, a judge might consider how a statute has been—or will be—implemented. Although both purposivists and textualists may use any of these tools, a judge’s theory of statutory interpretation may influence the order in which these tools are applied and how much weight is given to each tool.
This report begins by discussing the general goals of statutory interpretation, reviewing a variety of contemporary as well as historical approaches. The report then briefly describes the two primary theories of interpretation employed today, before examining the main types of tools that courts use to determine statutory meaning. The report concludes by exploring developing issues in statutory interpretation.