Jamie Spencer provides some insight into what the "float test" is for boating while intoxicated, as mentioned in the Cedric Benson DWI arrest on Lake Travis, Austin, TX:

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 (ed. field sobriety tests) 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.

Read more from Jamie Spencer's Failing the 'Float Test' post . . .