Here's a new, non-politics example. The NFL is apparently trying to combat this credible deniability strategy in steroids:
In announcing the suspensions Tuesday, the NFL said it's not obligated to issue specific warnings about specific products. The league also reiterated the section of its policy that reads:
Yes, when your job is to tackle 300 lbs piles of muscle charging your direction at 22 mph, health and safety is of the utmost concern!
"You and you alone are responsible for what goes into your body. Claiming that you used only legally available nutritional supplements will not help you in an appeal. ... Even if they are bought over-the-counter from a known establishment, there is currently no way to be sure that they contain the ingredients listed on the packaging or have not been tainted with prohibited substances ...
"If you take these products, you do so AT YOUR OWN RISK! For your own health and success in the league, we strongly encourage you to avoid the use of supplements altogether, or at the very least to be extremely careful about what you choose to take."