Rebecca Eisenberg, a biomedical patent law expert at the University of Michigan, in a recent paper (available for download), reviews several studies and presents new evidence that reassess some early warnings about overactive biomedical patenting creating an “anticommons”.  She writes:

Most scientists report no difficulties in attempting to acquire IP-protected technologies, and only a small percentage report significant delays in research or having to abandon a project because of IP issues. Even in fields characterized by extensive patenting, many academic researchers seem to be either oblivious to the patents they might be infringing or unconcerned about potential infringement liability. More significant to researchers than patents as such have been practical restrictions on access to materials and data such as requirements for institutional assent to the terms of materials transfer agreements (MTAs).

See also: Rebecca Eisenberg’s faculty page and bibliography.