制定和执行政策的费用是确保对方遵守合同的条款,已及如果对方不遵守条款时采取适当行动（通常通过法律体系）的费用.
Policing and enforcement costs
are the costs of
（making sure the other party sticks to the terms of the contract,） and （taking appropriate action if THIS turns out not to be the case）.
这里的THIS是指 sticks to the terms of the contract遵守合同的条款