New England Wheels (“NEW”), a Billerica business that (among other things) retrofits vehicles for disabled drivers and passengers, seeks a declaration that it does not infringe two patents directed to retrofitting sliding doors in vans. Delphini, whom NEW asserts to be a non-practicing entity, first asserted these patents by sending a cease and desist letter in June 2019, accusing NEW’s Ford Transit, Ram Promaster, and Mercedes-Benz Sprinter retrofitted vans of infringing the two patents, but identifying no specific claims alleged to be infringed and providing no infringement analysis. As NEW had already moved away from retrofitting van doors, agreed to remove the portions of their website showing such and to cease and desist with so doing moving forward. Undeterred, Delphini responded by demanding a full accounting for past work, which NEW asserts is prohibited due to lack of notice that would preclude past damages. NEW noted that it had been retrofitting van doors since 2007, well before the patents were filed. NEW further noted that Delphini had sent cease and desist letters to other entities, using images from NEW’s website of both accused and un-accused products as proof of infringement, and demanded Delphini stop with this practice. When Delphini again responded with a demand for an accounting dating to the publication date of the earlier patent, NEW filed the instant declaratory judgment action, seeking a declaration that the two patents are invalid and not infringed and alleging tortious interference with advantageous business relations based on Delphini’s having sent cease and desist letters to customers and potential customers of NEW that included photographs of a new NEW product, the “Frontrunner” bus, suggesting that the bus infringes, despite Delphini having acknowledged to NEW that the Frontrunner does not infringe.