Archaeologists must follow both specific local, state and federal laws, and demonstrate sensitivity to those who may be related to the culture that they are investigating. Archaeologists, both professional and avocational, must be sure to have the permission of the landowners and tenants before going on private land. Collecting artifacts on federal and state property is illegal. Archaeologists must obtain permits to work on such properties, and must demonstrate that they have a significant purpose for doing the work.