In order to have a patent issued by the USPTO, the invention must satisfy four criteria: It must be useful, novel, non-obvious, and must meet what is known as the enablement criterion, meaning that it should have a detailed enough description that anyone working in the appropriate field should be able to make use of it. When a patent is issued, though, it gives the owner 20 years during which no one else can make, use or sell the invention.
In the United States, patents are issued according to the "first to invent" principle. This means that in the event patents are requested for the same invention by separate parties, whoever can prove that they made the invention first is the one entitled to the patent. This helped contribute to the mad rush of patent applications in the wake of the completion of the Human Genome Project -- everyone wanted to be first.
The majority of genetic patents are granted by the USPTO, or the European or Japanese Patent Offices.
In the case of patents like gene patents that involve altered products of nature, the inventor must deposit a sample of their product into one of 26 worldwide culture depositories as stipulated by the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the purpose of Patent Procedure. It is important to note that genes can count as altered products of nature only if they have been removed from the body and processed in some way. The patent applies to that processed end product.