Our attorney told us that a patent was just a license to sue.

As I recall there were several patents from the 60's and into the 70's dealing with accuracy of seed placement in the furrow relating to hill drop planters being made at that time. I was always told that patent law says that a patent application would not be approved if someone "skilled in the art" could have used , or combined prior published information to arrive at their design.

My opinion is that  Deere's as well as some of PP's patents will not and should not survive because of the prior patents listed below, (and others), that apparently were overlooked by the patent office examiners and were not cited as prior art during the application process.

Look at the following patents: #402305A, Hanson, Deere, 1975,  #3460720A , Peterson, Massey Ferguson 1967,  #3133515A, Beebe, Massey Ferguson, 1961.