For criminal concerns regarding retroactive ITAR additions, yes. However, significant civil financial penalties if congress so wished could still be constitutio

For criminal concerns regarding retroactive ITAR additions, yes. However, significant civil financial penalties if congress so wished could still be constitutional as the ex post facto clause has been held to apply exclusively to criminal matters starting in Calder v. Bull [1]. [1] https://www.oyez.org/cases/1789-1850/3us386 https://www.oyez.org/cases/1789-1850/3us386