Is non criminal one word or hyphenated?

Unless the Word is recognizable without the hyphen, it's best to hypenate. Would you know a noncriminal act? Perhaps, but the hyphen makes it clear:

The judge ruled that the defendant committed a non-criminal act.

Many Words we use today began as two Words, then became hyphenated, before eventually becoming one Word. The Word lipstick was originally two Words back in the 1880s, then became hyphenated around the 1920s.