It was not Percy suing Monsanto. Monsanto was suing Percy for a user fee and he opted to defend himself. He was not guilty of stealing their trait, he was guilty for selecting for it after he found contamination but he was not guilty for using the trait and therefore was not required to pay the exhorbitant user fee that Monsanto was suing him for.
This is the whole silly point about the GM patent, the product is not controllable but the patent still exists in its unwanted progeny and the patent is owned by Monsanto. If they own the patent, they own the gene and therefore should be liable for any economic loss their patented product causes. Its worse than your shirt theory because at least your shirt is not breeding while it is in the neighbours yard.

We as non-GM farmers don't want their patented GM seed, it is trespassing on our property and our legal defence is to sue the GM farmer under the same tort law as spray drift issues. The GM grower knows that they can not contain their product so they know that GM will drift over the fence and they should either take steps to avoid it or pay for any economic loss it causes.
Read the Nelsons case, Monsanto just dragged the court action out for years. Common sense did not play any part in their threatening action.

A subpoena of what information?

Laws are not adequate because they rely on precedents which is what Percy set. Why should a farmer dedicate so much time and money to fight Monsanto for something that should have been prevented in the first place?

No, I don't scaremonger without reason. I have not claimed farmers will be exposed to Monsanto/Bayer litigation since around 2002 when end point royalties were discussed at farm lobby level. I do say that we need to ensure a limit is set to ensure an end point royalty is not claimed for contamination.