A plain reading of the law about presidents on coins says the face of a living president should not be on currency. And yet President Donald Trump’s is, after his Treasury Department exploited a different law related to commemorative coins. The law says a president must not commit the US military into hostilities for longer than 60 days without congressional approval. The US has been in a conflict with Iran for more than six months, although the administration says it has taken time-outs in the war. Previous presidents from both parties have danced around this requirement, but nothing on the...