text: "The part of the picture you're missing is that he was off duty."
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  Perhaps officially. But cops are cops 24/7....carry a gun off-duty...and are normally authorized and even expected to take action if the "need" arises in front of them....like responding to a woman screaming for help or a person who needs medical attention, CPR.
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  Seeing someone "speeding" is not normally something any department would encourage an "off-duty" officer to take action on. Hit and run? Maybe. Speeding? No. 
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  But he did identify himself and plainclothes officers, detectives, and investigators contact people all the time for various reasons....including investigating crimes and making arrests. 
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  So she (1) should have known he was a cop (2) didn't know he was off-duty. 
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  Regardless, his department will review his actions....and apparently the court will review hers.