"Unusual methods of patent enforcement
One of my clients was involved in the design and manufacture of diving suits and equipment. He devised a lifejacket for use by divers for which we got a patent. He then devised a modification without telling me and started selling the modification. One day, I got a frantic phone call from my client. Two heavies had arrived at his premises and told him that he was infringing a patent and that unless he stopped immediately they would “sort him out”. My client wanted to know what he should do. I told him that the usual method was for the patentee to inform an alleged infringer of the existence of the patent and give him time to consider his position and reply. My client said that he did not think that this would work in this case and that he was going to tell the heavies that he would stop immediately. However, he would like to know if I thought he infringed the patent. He was also going to look into the matter of police protection. I got hold of the patent specification and checked that the patent was in force and then advised my client that I did not think that there was any infringement.