The way law enforcement works is if you brought enough attention to yourself, say by getting caught selling some, your bank/debit/credit transactions would be subpoenaed along with the records of the suppliers you were found to be doing business with. You don't have to be caught with over 200 gals on hand, they just have to prove you bought enough ingredients to produce that much.
That may indeed be how law enforcement would go about it, tubercle, but I think the authorities would be up a creek if that's all they had to go on. The statute specifically says "any adult may . . . produce beer" up to the prescribed limits. So, I think they'd actually have to prove that you produced beer in a quantity that exceeded the prescribed limit within a single calendar year. A purchase of 5000 lbs of malt and 50 lbs of hops could just be stocking up before our future Chinese overlords artificially spike our commodities prices!
Chinese overlords...I like that
Not a bad idea. Who knows?
I said what I did because this is really how its done. Innocent until proven guilty? Not always. I never dealt with anything alcohol related but I have drug dealers (yes, The Tubercle was a narc...10 years worth, but that is now a former life) and this is how things are usually done with the big guys. Can't get 'em any other way? Drop a dime to the IRS. There is a big difference though. All the ingredients to make beer are legal, its just the amount produced when the various things are brought together to make a product where "illegal" (actually controlled) substances are usually not, with the exception of some, like meth and some others that use legal over -the-counter products to make controlled substances.
The point I was trying to make is in response DHACKER's "Then an almost impossible law to enforce ". Never underestimate the IRS. They are on a mission.