> some sort of mechanism for variable-length IP duration is needed
I've always liked the idea of a Harberger tax-style patent enforcement fee:
The patent owner declares the value of their patent on an annual basis and pays 1-5% of that declared value per year for the privilege of relying on the government to enforce their exclusive ownership of the patent. At any point, another party can buy the patent at its declared value, which discourages patent-holders from declaring artificially low values. The annual fee discourages artificially high valuations for indefinite periods of time -- as the patent yields less return over time it makes less sense to keep paying a high annual fee, encouraging owners to lower the declared valuation or end the patent protection altogether when it's no longer profitable.
To discourage hoarding patents indefinitely one could either set a hard upper limit (e.g. 60 years) or increase the fee over time, for example every few years the fee increases by 1% until at some point the patent is effectively publicly owned.
I've always liked the idea of a Harberger tax-style patent enforcement fee:
The patent owner declares the value of their patent on an annual basis and pays 1-5% of that declared value per year for the privilege of relying on the government to enforce their exclusive ownership of the patent. At any point, another party can buy the patent at its declared value, which discourages patent-holders from declaring artificially low values. The annual fee discourages artificially high valuations for indefinite periods of time -- as the patent yields less return over time it makes less sense to keep paying a high annual fee, encouraging owners to lower the declared valuation or end the patent protection altogether when it's no longer profitable.
To discourage hoarding patents indefinitely one could either set a hard upper limit (e.g. 60 years) or increase the fee over time, for example every few years the fee increases by 1% until at some point the patent is effectively publicly owned.