This search may be expensive. The Public Search Room of the Patent and Trademark Office is the primary source of information. Also, Patent and Trademark Depository Libraries have been established at the Illinois State Library in Springfield and at the Chicago Public Library. When a patent is granted, an inventor must pay an issuance fee. Also, maintenance fees for the patent are paid three times during the patent period to keep the patent in force.
Patent law is a highly specialized area of legal practice.
The Patent and Trademark Office maintains a register of attorneys and agents who have met the legal, scientific, and technical requirements to practice patent law, and who have agreed to uphold high standards of professional conduct. While many reputable governmental and private organizations assist inventors to market inventions, you should be cautious in dealing with groups who undertake marketing efforts for an up-front fee. Experience has shown that many have very low success rates and derive their main income from inventors, not from successful marketing of inventions. Before entering into any substantial agreements involving fees for development services or accompanied by high pressure sales tactics, consult your legal counsel.