Can our general lawyer write patent applications and represent us before the U.S. Patent Office?

No, not usually. According to federal statute and the Patent Office rules, an attorney cannot represent a client before the Patent Section of the U.S. Patent and Trademark Office unless that attorney has been certified for prosecution by the Office. To be registered or certified, an attorney must have a technical background sufficient to question the inventors, such as an undergraduate engineering degree or a degree in the physical sciences, and that attorney must have passed a bar exam geared specifically for patent prosecution.