This past week on Patinformatics.com the focus was on WO documents with two posts on this topic. In the first, it became clear from an analysis conducted that while the use of the PCT system by US applicants has flattened out recently, and as a percentage is not dominated by them as much as it used to be, WO documents still play a critical role in the filing strategy of US organizations. In particular, a dramatic shift in the use of PCT applications occurred, and could be clearly seen, following the implementation of the AIPA in the early 2000's .
In the second post, the question of multiple documents, from the same authority, in extended families, but this time looking at WO documents was revisited. As was seen previously, in the case of European patents, when US patent documents are taken out of the equation, it is pretty rare to find extended families with more than one WO A1 document in it. The situation changes significantly though when US documents find their way into the extended family. When this occurs there is a much higher likelihood that multiple WO A1 documents will be found in the extended family. This post also demonstrated how significant the issue of multiple-application number occurrences are with WO documents that list the US as the priority country.