About 12 years ago, a police officer told my father that the hooks on our trailer's safety chains were now illegal and that we had to have closed links (safety clips, carabiners etc.). He said he could give us a ticket for just having the hooks but would just give us a warning for now.
He also said that we had the hooks upside down... (the openings were facing down/the road) and that a bump could jump them off the hitch which makes sense. So, we hooked them the other way and went on out way.