The patenting of OncoMouse had a significant effect on mouse geneticists, who had previously shared their information and mice from their colonies openly.

European patent application 85304490.7 was filed in June 1985 by "The President and Fellows of Harvard College".

[6] The case was eventually remitted to the first instance, i.e. the Opposition Division, with the order to maintain the patent on a newly amended form.

However, revocation of the patent was eventually published on August 16, 2006, more than 20 years after the filing date (the normal term of a European patent under Article 63(1) EPC), for failure to pay the fees and to file the translations of the amended claims under Rule 58(5) EPC 1973.

In 1988, the United States Patent and Trademark Office (USPTO) granted U.S. patent 4,736,866 (filed Jun 22, 1984, issued Apr 12, 1988, expired April 12, 2005) to Harvard College claiming "a transgenic non-human mammal whose germ cells and somatic cells contain a recombinant activated oncogene sequence introduced into said mammal..." The claim explicitly excluded humans, apparently reflecting moral and legal concerns about patents on human beings, and about modification of the human genome.

Two separate patents were issued to Harvard College covering methods for providing a cell culture from a transgenic non-human animal (U.S. patent 5,087,571; filed Mar 22, 1988, issued Feb 11, 1992, expired Feb 11, 2009) and testing methods using transgenic mice expressing an oncogene (U.S. patent 5,925,803; filed Sep 19, 1991, issued Jul 20, 1999, expires July 20, 2016).