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Patent Infringement Lawsuit: How to Sue & Defend Against Claims

Patent infringement lawsuits allow patent holders to enforce exclusive rights. Understanding how to bring a claim -- and how to defend against one -- is essential for innovators and businesses.

Content Type

Legal Guide

Venue

Federal courts exclusively

Min. Damages

Reasonable royalty

Willful

Up to 3x damages

What Constitutes Patent Infringement

Direct infringement occurs when someone makes, uses, sells, or imports a patented invention without authorization during the patent term. The analysis compares each element of the patent's claims to the accused product. If the product contains every element of at least one claim, it infringes (literal infringement).

Indirect infringement includes inducement (encouraging others to infringe) and contributory infringement (selling components specifically for infringing use). Both require knowledge of the patent.

Key Defenses

Non-infringement (product doesn't contain all claim elements); invalidity (prior art, obviousness, inadequate written description -- raised as defense or through PTAB inter partes review); license; and patent exhaustion after an authorized sale.

Patent Infringement Damages

Damages must be at least a reasonable royalty -- what a hypothetical negotiation would have produced. Lost profits are available when the patent holder can prove it would have made the infringer's sales. Willful infringement can result in enhanced damages up to 3x, plus attorney's fees.

How to Get Legal Help

If you believe you qualify based on the eligibility criteria described above, the next step is a free consultation with an experienced attorney. Most plaintiff-side attorneys handling these cases work on contingency -- meaning you pay nothing unless your case results in a recovery. Bring any relevant documentation including receipts, correspondence, or evidence of the harm you experienced. Related: Lawsuit Against Employer.

To stay current on case developments, claim deadlines, and settlement news, bookmark this page and subscribe to LawsuitWatch alerts. Coverage is updated as new court filings, settlement announcements, and eligibility changes are made public.

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Patent Infringement Lawsuit: How to Sue & Defend Against Claims: Frequently Asked Questions

Answers to the most common questions about this case and your legal options.

How do I sue for patent infringement?

Hire a patent litigation attorney, conduct a claim chart analysis, file in federal district court.

What defenses exist?

Non-infringement, invalidity, license, and patent exhaustion are the primary defenses.

How much are patent infringement damages?

At minimum, a reasonable royalty. Lost profits where provable. Willful infringement triples damages.

What are patent claims?

Numbered sentences at the end of the patent defining what is protected. Infringement analysis focuses on the claims.

Do I need a patent to sue?

Yes -- you must own or exclusively license the patent.