About Charles L
Charles L Riddle represents clients in trademark matters before federal courts and administrative tribunals. He appears in the Third Circuit and the Federal Circuit and is admitted to practice in Pennsylvania and before the United States Patent and Trademark Office. His practice spans both prosecution and contested proceedings at the PTO as well as litigation and appeals in federal court.
Riddle's career has involved work on oppositions, cancellations, trademark applications and appeals. He has taken cases through the Trademark Trial and Appeal Board and argued on appeal where statutory and procedural questions intersect with the marketplace. He handles the filing and defense of trademark applications, seeks provisional relief where appropriate and manages long-term clearance strategies for businesses of varying sizes. He regularly drafts briefs and motions for administrative proceedings and for federal appellate dockets.
Across his practice, Riddle deals with questions of distinctiveness, likelihood of confusion and scope of rights. He addresses the interplay between trademark law and related areas such as unfair competition and false advertising. His work often requires fact development, deposition practice and coordination with clients on brand policing, licensing and enforcement outside the courtroom. When a matter proceeds to appeal, he has experience preparing the record and the appellate briefs required by the Third Circuit or the Federal Circuit.
He maintains a presence in several regional offices. His practice includes work out of offices in Philadelphia and Allentown under the Esquire Trademarks name, as well as related operations serving Baltimore and Pittsburgh. That geographic spread allows him to respond to local and interstate trademark concerns and to appear where federal jurisdiction or PTO practice calls for an in-person presence.
Colleagues describe his approach as methodical. He emphasizes procedure and the careful marshaling of evidence. He structures cases to address early procedural risks and to preserve issues for appeal when necessary. In 2026 he continues to handle a mix of prosecution, enforcement and litigation matters for trademark owners and entities evaluating their mark portfolios. He maintains an active practice focused on trademark prosecution, enforcement and appeals.
