An attorney who has expertise and specializes in all areas relating to patentss is called a patents trademark attorney. If you need to get a patents / trademark or someone is infringing on your patents / trademark, then you will require a patents attorney.  When you need to file an application for a patents or have other legal concerns on intellectual property than you need a patents attorney.  To become a patents trademark attorney you have to have a degree or background in technology, science, or engineering.