Describe aspects of customs valuation practices that are controversial in the world of international trade, such as how countries establish import tariffs

Also, how does the WTO protect against potentially abusive practices when determining appropriate tariffs.

Countries that seek to provide high levels of protection to local industries and/or want to increase tariff revenues have often instructed customs officials to use methods that would raise estimates of the values of imports, such as adding a fixed percentage to the listed price of the import to cover the cost of freight and insurance. Often practices such as these would lead to corruption, since importers would seek to cut deals to secure lower valuations and pay lower tariffs. Article VII of the WTO agreement states that tariff systems must "conform to commercial realities, and outlaw the use of arbitrary or fictitious customs values."