Failing the 'Float Test': Boating While Intoxicated

I usually don’t pile on when a celebrity as arrested and the best way to do that is to not blog about the arrest. And while it’s worth noting that I have no personal knowledge of the facts in this case, nor do I represent the accused, this post is at least nominally in defense of Cedric Benson. (And to further my bona fides on sticking up for Benson, see this post.)
This part of the AP story about Cedric Benson’s arrest for Boating While Intoxicated in Austin jumped out at me:
According to a sergeant from the Travis County Sheriff's office, Benson, who played at the University of Texas in Austin, was arrested by the Lower Colorado River Authority. A LCRA spokesperson said that Benson, who failed a sobriety "float test" (an abbreviated version of a field sobriety test) on the boat, argued over taking a follow-up test on land and refused to put on a life jacket.
So they’re calling it a “float test” now. Never heard that one, but lemme take an educated guess at what they’re talking about.
Prior to taking someone to shore, a law enforcement officer asks the subject – in this case Chicago Bears running back Cedric Benson – to do some tests to prove his sobriety while he is still standing on his boat. While it’s on the water. Moving around. Waves underneath the boat.
Once the subject is unable to prove to the officer’s satisfaction that he isn’t intoxicated, he is asked to come ashore and then the standardized field sobriety tests are administered.
Putting aside for the moment that the FSTs are junk science at best to start off with, the officer then testifies in court – because it’s consistent with his training – that a 15 minute waiting period after coming off the boat is sufficient for the subject to regain his land legs, and to do the tests in a manner that puts him on equal footing with someone that hasn’t been out on a lake all day.
This 15 minute time period, as far as I’ve ever been able to tell, is completely made up. There are absolutely no scientific studies to show this. I’ve always suspected that whoever came up with it basically ripped off the idea from the 15 minute observation period required by Texas DPS in a breath test case.
One last note: I’m not saying that Cedric Benson is not guilty – I don’t know. Perhaps he was tanked. More likely than not, there was at least evidence that he had consumed some alcohol. But there’s a really big difference between those two, and conducting what the news media, if not the police, are now calling a float test to determine where on that bell curve he was? If it was anything like the boating while intoxicated cases I’ve seen in my career, I wouldn’t put much stock in it.