trade secret claims. 10 or 15 years may not seem like a long time when considering human history or geophysical activity, but it's eons within the legal system. (You should consult with an intellectual property lawyer to be positive).
The clock started ticking ... As a general rule, you have a certain number of years (typically 3 to 5) to take legal action after your problem developed. For example, most states have adopted the Uniform Trade Secrets Act which has limit of "3 years after the misappropriation is discovered or by the exercise of reasonable diligence should have been discovered." In addition, there's a legal theory known as laches that could limit any damages you may have suffered because you waited too long to bring the suit. (Here are some of the other defenses that Companies A, B, and C could make to a claim of trade secret misappropriation.) Although it's not the same as a lawsuit for damages, you may be able to argue that the issued patents are invalid by having the patents reexamined.