Story, Joseph, Commentaries on the Conflict of Laws , 8th ed., Boston, 1883
330 245."

Indeed a broader principle might be adopted, and it is to be regretted that it has not been universally adopted by all nations in respect to foreign contracts, as it has been in respect to domestic contracts, that no man ought to be heard in a court of justice to enforce a contract founded in or arising out of moral or political turpitude, or in fraud of the just right of any foreign nation whatsoever.3

3Armstrong v. Toler, 11 Wheat. 258, 260 ; Chitty on Bills (8th ed. 1833), p. 143, note; Boucher v. Lawson. Cas. temp. Hard. 84, 89, 194 ; Planché v. Fletcher, Doug. 251; post, s. 255, 257.

Referring Principles
Trans-Lex Principle: IV.7.1 - Invalidity of contract that violates good morals (boni mores)
A project of CENTRAL, University of Cologne.