It is to check the status of the other side's right and how well it would hold up. A significant proportion of warning letters in practice rest on rights with defects: a trademark may be in opposition, invalidation or non-use cancellation proceedings, or exposed to cancellation for three consecutive years of non-use; utility models and design patents are not substantively examined, so inventiveness has never been assessed and the right is usually less robust than an invention patent.
Four steps.
1. Check the legal status of the right. Whether the claimant has standing, whether the right is still in force, and whether annuities and renewals have been paid.
2. Run a preliminary infringement comparison, and search at the same time for grounds of invalidity and for room to argue non-infringement — prior art, prior use, exhaustion of rights, fair use and so on.
3. Weigh the commercial timing. An imminent trade fair, a major e-commerce sales event or a product launch is often precisely why the other side has chosen this moment to apply pressure.
4. Settle the response. A non-infringement position, negotiating a license, an action for a declaration of non-infringement, or a request for invalidation.
One caution: stopping production, delisting products, or putting an admission in writing before the status of the right has been verified may be used as an adverse fact against you in later proceedings.
