A “simple search” for decisions had already been available on the FPC website since the very beginning, but I have noticed only recently that the FPC has meanwhile enabled much more detailed database queries:
A manual is also available. This search interface is definitely a valuable tool.
Note, however, that indexing is not exhaustive (e.g., a search for “Costs: Legal aid” in field “GL” does not result in any hits, but there are published cases that inter alia deal with this topic — but the respective tag has not been assigned).
Moreover, there is apparently a difference between the two fields “GL” and “GS”: Both are entitled “Subject”, but searching those fields with the same query yields completely different results. For instance, searching for “Assignment of patent” in field “GL” yields O2012_012 and S2012_009. However, searching for “Assignment of patent” in the field “GS” only results in S2012_005 — a hit that is not at all produced in the field “GL”.