Fields Laboratories holds a valuable patent (No. 758-6002-1A) on a precipitator that prevents certain types of air pollution. Fields does not manufacture or sell the products and processes it develops. Instead, it conducts research and develops products and processes which it patents, and then assigns the patents to manufacturers on a royalty basis. Occasionally it sells a patent. The history of Fields patent number 758-6002-1A is as follows. Date: 2010-2013 Jan 1. 2014 Activity: Research conducted to develop precipitator Fees paid engineers and lawyers to prepare patent application; patent granted Jan 1, 2014 Cost: $560,000 1,040,000 Dec 31. 2016 Legal fees paid to successfully defend precipitator patent 86,000 April 1 2017 Research aimed at modifying the design of the patented precipitator 155,000 226,000 July 1 2021 Legal fees paid in unsuccessful patent infringement suit against a competitor Fields assumed a useful life of 20 years when it received the initial precipitator 4 patent. On January 1, 2019, it revised its useful life estimate downward to remaining years. Amortization is computed for a full year if the cost is incurred prior to July 1, and no amortization for the year if the cost is incurred after June 30. The company's year ends December 31.