Groklaw - Patents - Which Ones Are More Likely to Be Asserted in Litigation:

This likely won't be everyone's cup of tea, but there is an interesting academic paper by Professor Colleen Chien of Santa Clara University School of Law entitled "Predicting Patent Litigation." You can download a free copy of the paper here [PDF] on the Social Science Research Network. 

The paper is interesting because Prof. Chien identifies a number of objective markers that identify a patent as being more likely of being asserted in litigation than the general population of patents. The really useful aspect of her analysis is that many of these markers can be discerned prior to the patent actually being asserted.

Some of these markers are what Prof. Chien refers to as "intrinsic characteristics," i.e., characteristics that are in inherent in the patent itself. Such intrinsic characteristics include:

• they have more claims than unlitigated patents;
• they have more prior art citations (indicating that they have been more thoroughly vetted at examination);
• they are typically found in families of related patents;
• they are more likely to be originally assigned to the inventor or to a small company; and
• they are more likely to be issued to a domestic U.S. company than a foreign company.