A more thorough explanation:

The Bayh-Dole Act is a federal law that allows small businesses and nonprofit organizations to own or license inventions made while participating in federally funded programs. If an entity funded by the government creates an invention during a federally funded program, they must disclose it in a timely manner. The entity can choose to keep the rights to the invention and file a patent application. However, the government can still intervene and require the entity to grant licenses in certain situations.

March-in rights are the government's ability to step in and grant a new license or revoke an existing license if the owner of a federally funded invention (or their licensee) has not adequately developed or applied the invention within a reasonable time. For example, if a company receives government funding to develop a new drug but fails to make it available to the public, the government can step in and require the company to license the drug to other companies who can make it available to the public.

One example of the Bayh-Dole Act in action is the development of the hepatitis B vaccine. The vaccine was developed by researchers at the University of California with the help of government funding. The university was able to retain the rights to the vaccine and license it to a pharmaceutical company, which made it widely available to the public.

Another example of march-in rights being used is in the case of a company that received government funding to develop a new technology for cleaning up oil spills. The company failed to bring the technology to market, so the government stepped in and required the company to license the technology to other companies who could use it to clean up oil spills.