Border guards are arresting people who leave water for people trying to cross the border from Mexico into the United States. What laws are these people breaking?
It appears just one was arrested. Others were simply charged, the four going to trial though seems to be retaliatory to me since they appear to have gone back in the records to charge them for something that was initially thought to be dealt with when they were told to leave and did.
This article mentions most of the charges , ranging from littering to harboring.
https://www.google.com/url?sa=t&source=web&rct=j&url=https://reason.com/blog/2019/01/15/trial-begins-for-aid-workers-accused-of/amp&ved=2ahUKEwiYic_Y7t_gAhXmmq0KHbUbC7IQFjADegQIBxAB&usg=AOvVaw11Lxbt_mjfjbqfDdH9SFF2&cf=1
The volunteers are leaving jugs of water in a restricted federal wildlife refuge that requires a permit to enter.
Littering? Trespassing? Entering a no-no zone? Disturbing Wildlife? I’m quite sure there might be some bureaucratic reason to escalate the problem to be considered as breaking some law, if necessary. But, but. That is not unique to that territory. Not sure why, but I’m sure I ain’t only one that visualizes Breaking Bad landscape with all the props and baddies when this topic arises.