And who interprets it as per the constitution. SCOTUS . They have to make a ruling and enforce it . Even SCOTUS majority decision didn’t go far enough what some here think the 2nd amendment says . Kavanaugh’s concurrent opinion flat out says permit requirements are allowed. Other justices say something else. Some things are clear cut . Other things are in dispute.
But here is the military oath which is similar to the oath officers take:
"I, _____, do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; and that I will obey the orders of the President of the United States and the orders of the officers appointed .
Note the obey the orders part . It’s where the conflict is the rub. If 4 out 9 Justices can’t get it right, you can’t expect every cop to either
Lots of people on the job use this as an excuse to break their Oath. Lots of officers.