Proving patent infringement requires demonstrating that accused products or processes practice the elements of your patent claims. This analysis involves detailed technical comparison between claim language and accused technology, often requiring expert testimony and extensive discovery. Understanding how infringement is proven helps patent owners build strong cases and assess infringement risks.
Claim Construction
Before infringement can be determined, courts must construe the patent claims to establish what they mean. Claim construction is a legal question decided by judges, not juries. The process examines claim language, the patent specification, prosecution history, and sometimes extrinsic evidence like dictionaries and expert testimony.
Claim terms often have specific meanings in patent law that differ from ordinary usage. Patent holders generally want broader interpretations covering accused products while defendants seek narrower constructions excluding their technology. Claim construction hearings, sometimes called Markman hearings, often determine case outcomes before trial.
Element-by-Element Analysis
Literal infringement requires that accused products include every element of at least one patent claim. Claims are analyzed element by element, comparing each limitation to the accused technology. If any claim element is missing from the accused product, literal infringement fails. This all-elements rule means narrow claims may be easier to design around.
The doctrine of equivalents extends infringement beyond literal claim language to cover technologies performing substantially the same function in substantially the same way to achieve substantially the same result. This doctrine prevents infringers from escaping liability through minor modifications that preserve the invention's essence while technically avoiding claim language.
Technical Evidence and Expert Testimony
Patent cases typically require extensive technical evidence explaining how patented inventions work and how accused products compare. Technical experts analyze claim elements, explain relevant technology to judges and juries, and opine on whether accused products infringe. Both sides typically present competing expert opinions on claim construction and infringement issues.
Discovery provides access to accused products, technical specifications, design documents, and source code needed for infringement analysis. Protective orders govern handling of confidential business information while allowing technical evaluation. Expert testing and reverse engineering of accused products may be necessary to establish infringement.
Induced and Contributory Infringement
Beyond direct infringement, patent law recognizes indirect infringement theories. Induced infringement occurs when defendants actively encourage others to directly infringe, with knowledge of the patent and intent that their actions result in infringement. Contributory infringement applies when defendants supply components especially made for infringing use with no substantial non-infringing applications.
Indirect infringement requires underlying direct infringement. The patent owner must identify someone who directly infringes, even if that person isn't a defendant. Knowledge requirements for indirect infringement mean defendants must have known about the patent, unlike strict liability direct infringement.
Building Your Case
Successful infringement claims require thorough pre-suit investigation. Analyze accused products against claim elements, consulting technical experts if needed. Document how each claim element appears in accused technology. Consider claim construction positions and how arguments might affect your claims. This preparation strengthens complaints and helps anticipate defenses.