Lerner symmetry theorem

{{Short description|Result used in international trade theory}}

The Lerner symmetry theorem is a result used in international trade theory, which states that an ad valorem import tariff (a percentage of value or an amount per unit) will have the same effects as an export tax. The theorem is based on the observation that the effect on relative prices is the same regardless of which policy (ad valorem tariffs or export taxes) is applied.

The theorem was developed by economist Abba P. Lerner in 1936.A. P. Lerner, 1936. "The Symmetry Between Import and Export Taxes", Economica, N.S., 3(11), pp. [https://www.jstor.org/discover/10.2307/2549223?uid=3739936&uid=2&uid=4&uid=3739256&sid=21101757215053 306]-313.Jagdish N. Bhagwati, Arvind Panagariya, and T. N. Srinivasan, 1998 Lectures On International Trade, 2nd Edition, MIT Press. [http://mitpress.mit.edu/books/lectures-international-trade Description] and ch. 12, sect. 12-6, Lerner Symmetry Theorem, scrollable preview, pp. [https://books.google.com/books?id=zKC6EsxVb8kC&dq=%3Dfalse&pg=PA215 215-19.]