You're missing the point. The base cops are gonna pull you over and then call the civilian cops to come arrest you. Then you have to deal with both sides of the situation.
i didn't miss the point. You declared my post 100% not true and I explained my post how informal policy may effect prosecution on and off base. I would hazard to guess that you are not completely familiar with how the UCMJ or state laws operate and are posting what you have heard or observed. I am speaking from experience worky multiple prosecution cases (in addition to DUI) and working through the legal and administrative system to process charges. There are informal policies behind the scenes both on and off base that govern which are pursued based on evidence and circumstances.
You state "most bases have agreements with local law enforcement" to come get you if you get a DUI on base. Now your discussing jurisdiction agreements, same way that a base cop can pull you over outside the front gate. How large are most bases that you are referring to? Smaller bases may utilize the facilities from out in town. Large bases have the facilities to fully process the individual. I am not denying that there may be local base commanders that are working to bring multiple avenues of prosecution against service members. Heck I've been on two bases that had base cops camping out outside the Oclub when we still had them gleefully targeting officers. Base commanders meeting helped get rid of that and find a better solution (BOQ rooms set aside for those too intoxicated to drive etc). At larger bases there are even more collaborative coordination efforts with liaisons positions and information sharing. But I would posit from my experience (some recent) that not all bases have the townies come get you from on base if you get a DUI. As always situation dependent.
But my main point and my posts have been how big navy can process DUI charges. It doesn't matter if it happened on or off base (your scenario is moot), the command can pursue via the UCMJ NJP or higher as long as you think you have the evidence and your command wants to pursue it. I personally would prefer for it to be handled on base, get a blood draw or urine sample for bac level etc through the military resources on base etc. depending on locale, if townies takeover you (the command) may not even get access to the final police report! Unless the service member is stupid enough to give a copy to the command they may not even have the evidence necessary to pursue! And yes I have had service members willingly give statements or paperwork that can be used against them to military officials. Once again get legal advice first.
If you are over the BAC legal limit on or off base you are going to have a hard time and one or both sidea of the legal system (local or UCMJ) will prosecute you. If it's just a field sobriety test failure and below BAC likits a good lawyer can probably get you off with a charge reduction or dropped charges out in town. On base it just depends on the evidence and if the service member wants to roll the dice that the command doesn't have enough evidence to support a court martial case.
Administrative actions such as driving privileges on or off base can be happening seperatley and of course have different levels of evidence.
