Abstract
We describe a system to execute U.S. federal bills into law, as part of a working application for the United States House. This system is based on a formal grammar we developed, which achieves greater than 94% accuracy in parsing amendatory phrases in bills; it is in production at the United States House of Representatives and is used to produce official ‘Comparative Print’ reports showing how a bill would amend current law. The grammar consists of two components: CItation Modeling and Processing Language (CIMPL), which captures citations to current law as they are found in bill amendments, and AMendment Processing Language (AMPL), which includes directive language to amend the text referred to by the CIMPL phrase. Here, we describe the analysis that led to development of the grammar, and provide an overview of how the grammar is applied to execute proposed amendments in the Comparative Print Suite of the U.S. House of Representatives. This application is available to all Members and staff at the internal site, compare.house.gov. Both the executable grammar and the full, point-in-time U.S. law dataset upon which they act, are publicly described here in technical detail for the first time.