I've heard it both ways. Some say it is and others believe not. I think it will depend on how the law will be interpreted if bought to a court's attention.
Eisbock beer created via freeze distillation of doppelbock beer. Increasing the strength of beer by "freeze distillation" is the process of enriching the beer by partially freezing it and removing frozen material that is poorer in alcohol than the liquid portion left behind. The question is whether or not the law will interpret this process as distillation.
According to 26 USCS § 5002 the terms distilled spirits, alcoholic spirits, and spirits means “substance known as ethyl alcohol, ethanol, or spirits of wine in any form (including all dilutions and mixtures thereof from whatever source or by whatever process produced)."
I'm not a lawyer but there are some members here that are...maybe we can get some interpretation from them.
Edit:
I mean, would ya ask your lawyer about mash temps?
If his name was Pawtucket Patriot, you certainly could! 
I would echo Denny's advice though. Local alcohol-related regulations are often very complex. If you're unsure about being in compliance, you should seek out a local attorney with specialized knowledge of the regulations in your jurisdiction.
...and look who chimes in while I'm typing.
Sounds like great advice Matt and Denny.
