Of course there should be a law against taking artifacts from archaeologic sites and laws against disturbing the sites by digging. These sites should be posted

Of course there should be a law against taking artifacts from archaeologic sites and laws against disturbing the sites by digging. These sites should be posted though, much the same private land is posted "no hunting". Instead of throwing the law out, require that the onus be on the site owner to inform people that the site is, in fact, protected.