The US, as a signatory to the major treaties on the laws of war has an obligation to enforce the customary and treaty norms of proper behavior in wartime not only within our own forces but by allied and opposing forces. This is not just a support task but in cases where opposing forces deliberately violate the laws of war, it is an operational responsibility that, when we fail to carry it out, cedes vital military advantage to law breaking enemies and increases the dangers that civilians face within war zones.
It would be interesting to read the operational planning document that lays out how we are supposed to undertake such operations. So far as I can tell, nobody has written such a document. We just don’t view military lawyers as anything other than a support element that helps other units undertake other military operations.
The operations documents are published by the Joint Chiefs, listed in the Joint Electronic Library. Classified planning documents have a link into the non-public JEL+ so the missing document can’t be put down to a problem of state secrets keeping the document out of public view.
Until we reformulate our doctrine and start taking laws of war enforcement as a military operation against enemies that tend to violate these laws en masse, excess casualties will be an inevitability. Most of those casualties will be non-military civilians of whatever country we happen to be fighting in but a significant amount of them will wear US military uniforms.