Originally Posted by
ND Sol
I am somewhat confused as to what happened. Why would the TSA go on to an airplane to pull someone off if he had already cleared security with these "prohibited" items? Shouldn't the issue have been raised and resolved at the screening checkpoint?
Based on the OP's description, there were multiple tools and batteries involved, so OP's friend had likely checked the batteries rather than carrying them on/bringing them through the screening checkpoint.
On one hand, I would assume that a "major power tool manufacturer" that "has a team of lawyers" would be aware of DOT regulations on transporting LI batteries on passenger planes and would communicate these regulations to their employees. If the OP's friend was within the rules, then he has a case against TSA. However, since the OP asked "Anyone know what the real rules are concerning LI_Ion (or any other batteries) on a plane?", I wonder if the OP's friend knew the rules. If not, the OP's friend could have violated the regulations (albeit unkowingly).