For information on legal research in Puerto Rico, see The Challenge of Puerto Rico Legal Research: What's Available & How Do You Find It by Maria M. Otero. For links to online resources, see The Guide to Online Law: Puerto Rico by the Law Library of Congress.
Legislation: Puerto Rico session laws are published in The Laws of Puerto Rico, which is posted free in English from 1997 to the present by the Office of Legislative Services. Selected session laws in English back to 1988 are searchable on Lexis (PR;PRALS) and Westlaw (PR-LEGIS for relatively recent laws; PR-LEGIS-OLD for older laws). Session laws are available in Spanish on Westlaw (PRS-LEGIS for relatively recent laws; PRS-LEGIS-OLD for older laws back to 1990) and, if you subscribe, back to 1980 in the Digital Session Laws Collection on HeinOnline.
Puerto Rico laws are codified in the Laws of Puerto Rico Annotated, which is available on Lexis (PR;CODE), Westlaw (PR-ST-ANN) and MicroJuris. Lexis posts a free, unannotated edition in English and Spanish. Lexis has historical editions of the annotated code back to 1988 (e.g., PR;PR1988).
Judicial Opinions: Supreme Court cases are published in Spanish in Decisiones de Puerto Rico (the D.P.R. or P.R. Dec.) from 1899 to about five or six years back. They were also published in English in the Puerto Rico Reports (the P.R.R.) from 1899 to 1972 or 1978. After that, they are published in the Official Translations of the Opinions of the Supreme Court of Puerto Rico which, like the Decisiones, is about five or six years behind.
La Rama Judicial de Puerto Rico
posts Supreme Court decisions free in Spanish from 1988.
Lexis has Supreme Court a database with Supreme Court from 1899 to present and Court of Appeals from 1996 to present (PR;PRCTS). MicroJuris also has these decisions, as well as "Opinions of the Secretary of Justice."
Westlaw has Supreme Court cases in English, along with decisions of the U.S. Federal courts for Puerto Rico (PR-CS-ALL).
The Bluebook: A Uniform System of Citation has a section listing Puerto Rican case reporters.
Regulations: If you subscribe, MicroJuris offers regulations from dozens of Puerto Rican government agencies. The Puerto Rico administrative code, Reglamentos Del Estado Libre Asociado De Puerto Rico, is available in Spanish on Lexis (PR;PRADMN).
Insurance: The Puerto Rico Insurance statutes, regulations and Bulletins are available in English on Westlaw in the PRIN-COMBINED file.
Libraries: For questions and copies of Puerto Rico legal materials not otherwise available, call one of the libraries at the University of Puerto Rico (787-999-9688, 787-999-9690 or 787-999-9714).
For more legal resources, see the Puerto Rico Resources page by the Georgetown Law Library.
Business: A law firm called McConnel Valdés writes a Guide for Doing Business in Puerto Rico.