Option 4 provides a noteworthy alternative in this regard. This option would provide incentives to local innovators to find such uses, both with respect to the adaptation of foreign substances to local conditions and also with respect to stimulating investment in new uses of substances rooted in traditional knowledge. As opposed to option 3 (utility models), a system of compensatory liability would not provide the right holder with the right to deny access of competitors to the protected subject matter for purposes of product improvement. This section considers briefly a third possible exclusion from patentable subject matter, i.e. pharmaceutical derivatives of existing medical products.