Orphan works are works that are currently under copyright restrictions, but there is no conventional way to determine who currently holds the copyright (note: this may occur for many reasons, including the fact that a publisher is no longer in business, or the copyright has passed to heirs who cannot be identified or located, etc.).
Unfortunately, US law does not currently provide a remedy to individuals who wish to use orphan works. However, a project at Harvard is currently under development to create an online list of orphan works in the library collection and (eventually) digitize the list of works if the author/rights holder does not respond to an open call for assistance from the rightsholder(s). The project, called the Orphan Works Project may eventually digitize and publish notable orphan works online in an open access format.
Q: If I can't locate the copyright owner of a work in order to ask permission and it is not a fair use, can I simply use the work?
A: Unfortunately, no. That's why the Orphan Works project was devised. Experts are trying to find an agreeable solution to this legal conundrum. But, for the time being, the answer remains no.