Law: U.S. Const. art. I, § 8, cl. 8 provides authority for patents. Most patent statutes are codified at 35 U.S.C.; regulations at 37 C.F.R. The MPEP provides guidance for patent examiners but has no legal force. The United States is also a party to numerous international patent treaties, including TRIPS and the PCT.
Cases: See my list of Supreme Court patent cases. The Court of Appeals for the Federal Circuit hears all patent appeals, and their website provides oral argument recordings and new opinions. See the "Quick Links" here for PTAB decisions. I assume people with Westlaw/Lexis access already know how to search cases there, but did you know that Google Scholar lets you restrict case searches by court (e.g., to search only Federal Circuit cases)?
Treatises: Chisum on Patents (CHISUM on Lexis) is the most cited; Westlaw has Moy’s Walker (MOY-PAT). If you are looking for free options that provide a good overview of patent law, the Patent Case Management Judicial Guide by Peter Menell et al. has a lot of basic information (and was updated in 2016).
Patents: Search U.S. patents and applications at USPTO, and use their PAIR system or the new Global Dossier to see a patent’s prosecution history (known as the "file wrapper"). The PTO also has a nice list of sites for international patent searches. For quick searches, I like Google Patents (which also lets you easily download PDFs). PriorSmart has a nice search interface that combines many patent search sites.
- General advice. Useful paid sites are ProQuest and Hein; Congress.gov and FDsys have recent documents for free. You need the bill number (e.g., H.R. 4482), which is at the top of the public law (e.g., Pub. L. No. 97-164). Search by bill number in ProQuest to quickly find committee reports and hearings. For more details, go to the Congressional Record in Hein and look at the “History of Bills” at the end of the relevant volume for both the H.R. and S. number (and if the bill passed in the second session of a Congress, look in both sessions). The numbers are pages in the record where the bill was amended, debated, etc.
- Leahy-Smith America Invents Act, Pub. L. No. 112-29 (2011). The only committee report is H.R. Rep. No. 112-98 (PDF), but on page 57 it notes that “the bill is a 6-year work in progress” and cites other bills and hearings. Joe Matal, who worked on the bill in the Senate, has discussions (with his own slant) here and here. The USPTO has compiled the legislative history.
- Patent Act of 1952, Pub. L. No. 82-593. UNH Law has a nice collection of the relevant legislative history here.
- Why search the legislative history? There is an interesting debate about the relevance of legislative history, but there are enough judges who think it is relevant that it seems like malpractice not to search the legislative history in a statutory interpretation case.
Datasets: For those interested in empirical work, the USPTO has research datasets and bulk data products, NBER has patent citation data, and WIPO has also compiled data for researchers. Lex Machina's patent litigation dataset is free for academics, nonprofits, and many government employees, and the free Stanford Patent Litigation Dataset has patent asserters coded by entity type. Patent scholars who create more tailored datasets for specific projects often make them public; see, e.g., John Allison's and my dataset of hand-coded dataset of § 112 decisions. If you can't find the dataset used for a given paper, don't be afraid to ask the author; responsible researchers should be willing to share unless doing so raises other ethical concerns.
International: This page is focused on U.S. patent law, but if you need to learn about IP laws in other countries or international IP treaties, WIPO Lex is a great resource.