How about the US Supreme Court:
See Carpenter v. Pennsylvania, 58 U.S. 456 (1854):
"The debates in the federal convention upon the Constitution show that the terms "ex post facto laws" were understood in a restricted sense, relating to criminal cases only, and that the description of Blackstone of such laws was referred to for their meaning. 3 Mad.Pap. 1399, 1450, 1579.
This signification was adopted in this Court shortly after its organization in opinions carefully prepared, and has been repeatedly announced since that time. Calder v. Bull, 3 Dall. 386; Fletcher v. Peck, 6 Cranch 87; 33 U. S. 8 Pet. 88; 36 U. S. 11 Pet. 421."