Good reading. Here is some food for thought:
When LE asks vague questions, such as have you been drinking, what are you doing here, the correct answer is:
"I will be happy to answer your questions as soon as you read me my miranda rights"
http://en.wikipedia.org/wiki/Miranda_warning has some good information too. Here is a quote" If they speak to police about the incident before invoking the Miranda right to remain silent, or afterwards at any point during the interrogation or detention, the words they speak may be used against them if they have not stated they do not want to speak to police."
In other words, if they ask you if you were drinking, and you say yes or no, that is probable cause.
If you don't answer and request your miranda rights, they can't continue fishing, and need probable cause. Why give them ammunition?
This defense may not be perfect, but it puts a burden on LE to have more than a hunch about something.