Refers to citations of a patent or patent application as prior art to subsequent patent applications; they usually start to appear within a few months of the patent being issued or the application being published. The number and rate of forward references for a patent is one way of assessing its value and importance. Forward references are normally done with a single type of patent, usually U.S. patents, which explicitly state prior art considered in their examination on their cover page. Another use of forward references is to look for potential infringers of technology, since the potential infringer’s own patent applications would be likely to cite the patent.
Most patent information databases offer the ability to do a forward reference check. When used in licensing negotiations, it is important to make sure that the forward citation analysis excludes or separately counts self-references, i.e., references in which the owner of a patent cites that patent (or its own publications, e.g., white papers) as prior art in its own subsequent applications. This is for three reasons:
(a) holders of patents tend to cite them because failure to do so would give rise to claims of inequitable conduct;
(b) holders of patents tend to know their portfolio and previous work well; and
(c) citing a patent allows a holder to raise the profile of its own intellectual property.
It should also be noted that the USPTO appears to cite as references patents filed by U.S. entities much more frequently than those of foreign entities, especially when the original language of the foreign parent patent application was not English.