How do I defend against a patent infringement lawsuit?

No. A demand letter alleging patent infringement does not mean the patent is valid or that your product or system actually infringes it. It’s a claim, not a final decision. However, every demand letter should be taken seriously and reviewed carefully rather than ignored.

Depending on the facts, your attorney may evaluate several possible defenses.

Invalidity. Whether prior art or other grounds could support a challenge to the patent’s validity. This position questions whether the patent being asserted against you should never have been granted in the first place, and therefore could not be enforced.

Non-infringement. Whether your product or service actually falls within the patent’s claims as written, which often turns on how specific claim terms are construed.

Licensing or standing issues. Whether the entity actually owns the rights it claims to be enforcing, or whether your company (or a supplier) already holds a license that covers the accused product.

Settlement or license negotiation. Whether resolving the dispute makes business sense based on the strength of the claims, potential exposure, and cost of litigation.

The appropriate strategy will depend on the patents, facts of the infringement allegations, and your business circumstances. Your patent counsel should determine which defenses and next steps warrant further investigation.

As early as possible, and this is might be the single most important step. A patent attorney can:

1. Assess the patents and infringement allegations
2. Verify ownership, enforceability, and validity of the asserted patents
3. Outline potential defenses
4. Advise on how communications should be handled

Early advice helps you avoid missteps that are hard to take back later, and gives you a clearer read on how serious the claim actually is.

For example, it is important to avoid making technical admissions or explaining how your product works without proper counsel. Statements made in an early response may later become relevant in litigation, particularly if the court interprets the patent claims differently from the position taken in your correspondence. This is a common claim construction “trap” that you want to avoid. When appropriate, counsel should handle communications with the patent owner.

Prior art is evidence that predates the relevant patent date and can be used to test whether a patent’s claims are truly new and inventive. It may come from earlier patents, technical publications, industry standards, products, manuals, and other source materials.

Even if a patent appears relevant to your product, it’s validity, and therefore enforceability, may still be challenged. Your patent attorney will determine whether a invalidity challenge is appropriate, while technical research helps uncover supporting evidence.

The review may begin with the patent itself: confirming that it was properly issued, remains in force, and is owned by a party with the right to enforce it. Counsel may also examine the patent’s prosecution history for statements or amendments that could affect the scope of its claims.

If counsel determines that patent validity should be investigated, they may recommend a prior art or patent invalidity search. These searches look for earlier disclosures that may be relevant to the asserted claims and could support a potential validity challenge.

No. Some cases resolve before trial through dismissal, settlement, licensing, or an inter partes review (IPR). An inter partes review is a mechanism within the USPTO to challenge the validity of the patent. This is considered as less inexpensive that court litigation.

Regardless of outcome or the avenue for the resolving the case, building robust evidence early matters.

A Non-infringementposition is one potential defense to a patent infringement claim. The basic question answered here is whether the accused product or technology falls within the scope of the asserted patent claims.

To evaluate this, patent counsel interprets the asserted claims and conducts a claim-by-claim comparison against the accused product or technology. Technical documentation, product specifications, source materials, and other evidence can help establish how the product operates and whether each required claim limitation is present. Counsel may also review the patent’s prosecution history and other evidence that could affect the scope or interpretation of the claims.

If the evidence supports it, a licensed patent attorney may provide a non-infringement opinion addressing whether the accused product falls within the scope of the asserted claims.

Parola Annalytics does not provide a Non-infringement Analysis or Opinion, but we have a network of patent attorneys who can help you. Get in touch.