Which U.S. patents can be extended?

The U.S. Patent Act was amended and approved into law on July 19, 1952, and has undergone three major revisions in 1975, 1984, and 1999, respectively. Now the term of the U.S. patent is effective from the date of authorization, the termination of the earliest application from the date of the full 20 years; In addition, the U.S. Patent Act provides for a number of statutory conditions, in order to meet the conditions of the patent term can be adjusted to extend the period of time. The original U.S. Patent Act, the patent term is 17 years from the date of authorization, in 1994, after the Uruguay Round of GATT negotiations reached an agreement in 1999, the United States amended the patent law will be changed to the patent term: from the date of application for 20 years. According to the U.S. Patent Law, if a patent application is filed before June 8, 1995 and is granted, or if the patent is still in force on June 8, 1995, the termination date of the patent right shall be the longer of the "filing date + 20 years" and the "grant date + 17 years". In order to compensate for the period of time during which patents are subject to administrative licensing, Title II of the Drug Price Competition and Patent Term Compensation Act (DPCA) was introduced in the United States in 1984. This Title extends the life of a patent to compensate the patentee for the time spent developing a new product and waiting for a government license, and applies to patents protecting pharmaceuticals for human use, medical devices, food products, or pigment additives. 1988 saw the entry into force of the Animal Generic Drugs and Patent Term Compensation Act in the United States. The Act extended the patent term compensation provisions to the field of animal drugs.The Uruguay Round Agreements Act, which came into effect on June 8, 1995, changed the life of U.S. patents. For patents granted before that date, the patent life extends for 17 years from the date of grant. For patents granted thereafter, the life extends 20 years from the filing date. However, this is not the actual patent life for pharmaceutical patents that require seeking a marketing license. Under the U.S. patent term reimbursement system, a patent can be protected for up to five additional years. However, in any case, the patent life of a product may not exceed 14 years from the date the product receives an administrative license. After obtaining said license, if the patent life reaches or exceeds 14 years, then the patent term cannot be compensated.