You’re assuming that this was an accident and that he didn’t do it on purpose (he absolutely did). Humoring this theory though, let’s consider your question:
**Q: **Should a cop survey his surroundings, including the ground, before restraining someone?
**A: **Yes, of course, you would be a fucking idiot not to. Furthermore, forcing a person into some sort of hazard and injuring them, even unintentionally, is a problem to be avoided.
How to prevent that?
Your idea seems to be to do nothing at all so I’ll start by saying that’s fucking stupid.
Some might say to abolish law enforcement, but honestly, with compassionate police training emphasizing de-escalation, harm reduction, and civil service, we might actually have an ethical system someday. Also by firing cops on the first offense for use of excess force and blacklisting them from law enforcement for years requiring re-certification to ever become a cop again. And abolishing police unions and narrowing legal immunity for on-duty cops so that they don’t get away with maiming and killing people. And not funneling all of the excesses of the U.S. Military Industrial Complex into the hands of every suburban police department so that they can act as a standing army in our turnkey dictatorship.