The patent system does not exist in a vacuum. Over the past half century, landmark legislation, Supreme Court decisions, and policy changes have fundamentally reshaped the rules governing patents -- who can get them, what can be patented, and how they can be enforced. These legal shifts have had profound effects on patenting behavior, with visible impacts on the trends shown throughout this book.
The timeline below chronicles the most consequential changes to US patent law and policy from 1980 to the present. Click on any event to learn more about its impact and the published academic research examining its effects.
Legislation
Court
Policy
International
1980
1982
1984
1994
1995
1998
1999
2003
2006
2007
2010
2011
2013
2014
2017
2018
2021
2023
Impact on Patent Activity
Several of the legal events above left visible marks on the patent data explored in earlier chapters:
Bayh-Dole Act (1980): Triggered a surge in university patenting. Government-funded patents (Chapter 7) began climbing in the 1980s as universities established technology transfer offices.
Federal Circuit (1982): Unified and strengthened patent rights, contributing to the overall upward trend in patent grants through the 1990s and 2000s (Chapter 1).
State Street Bank (1998): Established the patentability of business methods, precipitating a rapid expansion in software patent filings visible as the acceleration of Section G (Physics) and H (Electricity) patents in the late 1990s (Chapter 2).
America Invents Act (2011): Created the PTAB inter partes review system, providing a faster and cheaper alternative to litigation for challenging patent validity. The shift to first-inventor-to-file changed priority rules for all patents filed after March 2013.
Alice Corp. v. CLS Bank (2014): Dramatically narrowed patent eligibility for abstract ideas implemented on computers. Contributed to a visible slowdown in software-related patent grants in subsequent years.
The Patent Pipeline
How efficiently does the patent system process inventions? By comparing the number of patent applications filed each year against the grants issued, we can track the USPTO's throughput and the growing gap between filing and granting activity. The ratio of grants to applications reveals how the system's selectivity and backlog have evolved over time.
Patent Applications vs. Grants Over Time
Annual filings (by filing date) and grants (by grant date) for utility patents, with grant-to-application ratio. Note: Only patents that were eventually granted appear in this dataset.
Major legislative changes create visible inflection points in patent filing data, demonstrating the direct impact of policy on innovation incentives. The growing gap between applications and grants reflects increasing examination complexity and backlog.
Market Concentration
Are certain technology areas becoming dominated by a few large players? The Herfindahl-Hirschman Index (HHI) measures market concentration by summing the squared market shares of all firms in a sector. On the standard DOJ/FTC scale, below 1,500 indicates an unconcentrated market, 1,500-2,500 is moderately concentrated, and above 2,500 is highly concentrated.
HHI Concentration by CPC Technology Section
Herfindahl-Hirschman Index (HHI) for patent assignees within each CPC section, computed in 5-year periods. Higher values indicate greater concentration.
Despite concerns about market power in technology, patent markets remain remarkably unconcentrated across all sectors. Even in areas dominated by large firms, the broad base of innovators keeps concentration well below antitrust thresholds.
Technology Convergence
Are technology boundaries blurring over time? When a single patent spans multiple CPC technology sections, it signals that the invention draws on knowledge from distinct fields. The matrix below shows how often each pair of technology sections co-occurs on the same patent, measured as a percentage of all multi-section patents in each era.
Technology Convergence Matrix
Percentage of multi-section patents that span each pair of CPC sections, by era. Select an era to compare convergence patterns over time.
Technology boundaries are blurring over time, with the Physics-Electricity convergence intensifying as digital technology permeates nearly every domain. This increasing cross-pollination has implications for patent scope and examination complexity.
Having surveyed the legal and policy framework that governs the patent system, the next chapter turns to one of the most consequential applications of that framework: green innovation. The interplay between patent law, government incentives, and climate policy has shaped the trajectory of clean technology patents over the past five decades.
Legal information synthesized from primary sources including congressional records, Supreme Court opinions, and the USPTO. Event descriptions focus on patent-relevant impacts. This timeline is not exhaustive and focuses on the most consequential changes affecting the US patent system. Academic research summaries draw from published studies in leading economics and management journals including the American Economic Review, Quarterly Journal of Economics, Journal of Political Economy, Review of Economic Studies, Management Science, Strategic Management Journal, and Academy of Management Journal. HHI is computed using the standard Herfindahl-Hirschman Index formula (sum of squared percentage market shares) on patent assignees within each CPC section per 5-year period. The convergence matrix counts distinct CPC section co-occurrences across all CPC codes assigned to each patent (not just the primary classification). Applications vs. grants data uses PatentsView, which only includes patents that were eventually granted -- the "applications" count therefore represents successful filings rather than total submissions to the USPTO.