If you don't play online poker, chances are good you didn't notice that the U.S. recently banned it. So why should you care?

The other reason even non-gamblers ought to be concerned about all of this is that it will be difficult for the government to enforce this ban without giving law enforcement some exceptionally broad powers. Federal authorities can't arrest the owners of gaming sites because they're based offshore, in countries where gambling is legal (unless they're foolish enough to come to the U.S.). The only option, then, is to go after the gamblers themselves. That means deputizing banks, credit card companies, and Internet Service Providers to start monitoring their customers spending and web surfing habits. Because the penalties against these companies for violating the law are likely to be severe and because the law specifically exempts them from liability for over-enforcement, your bank and ISP are likely to err on the side of banning legal transactions and erroneously reporting you to federal authorities than to err on the side of leaving you alone.

(Emphasis mine.)