I disagree that this will help, because the established companies the pledge would apply to are a secondary problem and mostly seem to fight each other (has Microsoft asserted patents against a startup? has IBM? has AT&T? when they asserted patents it was against multi-million dollar businesses!). The primary problem is patent trolls (see e.g. lodsys / intellectual ventures) for whom this pledge could be considered s…
Everyone will game the IP tax by valuing it at pennies -- after all, they may not directly be using it may not have a fair market value before they take someone to court. As a real-life example of people gaming these types of taxes, people buy expensive (>100K USD) cars in europe directly (i.e. taking delivery in stuttgart) to save on the sales tax: driving it around for a bit ensures that the car is technically "use…
Of course, the easy work around to this is the claim that it's value increased suddenly when the patent became more useful; you start paying more tax when you start suing others.
Considering that low maintenance costs don't prevent domain squatting, I'm not sure this would be an effective tactic to prevent lots of silly patents.