It is in the news that a British geologist has been sentenced to 15 years for "intentionally taking or trying to take out of Iraq an antiquity", specifically 12 stones and shards of broken pottery which were in his and his college/friend possession as they attempted to leave the country. His main defense seems to be that he had no idea he was breaking Iraqi laws.
I know very little about archaeology, and less about laws around the world, but I would expect most if not all countries to prohibit the removal of antiquities without specific permission. I am also aware that one of the most important types of antiquity are pottery fragments, in terms of what we have learnt about history. I would expect a geologist with an interest in international archaeology to know more about laws regarding this than me.
What are the "usual" laws about taking such items out of a country? Any relevant jurisdiction would be interesting, but the best answer would compare multiple jurisdictions to give any idea of what someone who was familiar with this field might justifiably expect the law to be.