How to Use, and Not to Use, Proportionality Principle

41 Pages Posted: 26 Mar 2019 Last revised: 21 Jun 2019

See all articles by Yun-chien Chang

Yun-chien Chang

Academia Sinica - Institutum Iurisprudentiae (IIAS); New York University School of Law

Xin Dai

Ocean University of China

Date Written: March 3, 2019


The proportionality principle is used in constitutional law and administrative law worldwide. We argue that it has been used when it should not, and when it should, inadequately used. Our major arguments are that, first, the German theorist Robert Alexy’s influential formulation of the proportionality principle is wrong because the suitability and necessity tests are not, as he conceptualizes them, Paretian, and his weight formula is not useful in comparing multiple means. Second, the proportionality principle is an incomplete form of cost-benefit analysis, as it systematically ignores certain costs and benefits and thus does not always maximize social welfare. The structure of the proportionality principle incorporates loss aversion that cannot be easily avoided through re-framing. Third, the suitability test embodies the form of teleological argument, which requires a causal relation between means and ends. Hence, to appropriately conduct the proportionality principle, empirical legal studies that identify causal relationship are often required, particularly when strict scrutiny is adopted.

Keywords: the proportionality principle, Robert Alexy, weight formula, cost-benefit analysis, difference-making facts, teleological arguments, causal inference

JEL Classification: K23

Suggested Citation

Chang, Yun-chien and Dai, Xin, How to Use, and Not to Use, Proportionality Principle (March 3, 2019). NYU Law and Economics Research Paper No. 19-10. Available at SSRN: or

Yun-chien Chang (Contact Author)

Academia Sinica - Institutum Iurisprudentiae (IIAS) ( email )

128 Academia Sinica Rd., Sec. 2
Taipei City, 11529

New York University School of Law ( email )

40 Washington Square South
New York, NY 10012-1099
United States

Xin Dai

Ocean University of China ( email )

5 Yushan Road
Qingdao, 266003

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