If it is unenforceable, then for all intents and purposes, it is legal.
A law that is not capable of being enforced is not a law. It is a joke.
John Kerry will tell Japan that this is not acceptable!
19th century thinking in the 21st century and all that.
Unenforceable laws can have a purpose. Take the anti-sodomy laws, for example. As far as I know, police have never knocked down doors trying to catch people in the act. The purpose of the law was to serve as a basis for other related laws, such as laws prohibiting gay "marriage," prohibiting the promotion of homosexuality in public, prohibiting the promotion of homosexuality in public schools, prohibiting the adoption of children by homosexuals, etc.
As we have seen, the floodgates opened as soon as the Supreme Court struck down anti-sodomy laws.