Are there specific laws that deal with rate limits? Honest question - I get that something too fast could be considered DDoS, but so long as it’s below a certain threshold wouldn’t it be okay (not sure how said threshold would be determined)?
In the US, CFAA prohibits causing "damage", which includes "impairment to the integrity or availability" of data or systems. But as with many other things in law, it boils down to the court trying to assess your intent, whether you could've reasonably anticipated the outcome, and what that outcome ended up being.
There's no law that says "you can't send more than n packets per hour".