It seems they want to cover more than just lack of due negligence.
(2) gross negligence (i.e., conscious indifference),
is also an option.
http://www.dictionary.net/negligence
NEGLIGENCE, contracts, torts. When considered in relation, to contracts, negligence may be divided into various degrees, namely, ordinary, less than ordinary, more than ordinary. 1 Miles' Rep. 40. 2. Ordinary negligence is the want of ordinary diligence; slight or less than ordinary negligence, is, the want of great diligence; and gross or more than ordinary negligence, is the want of slight diligence. 3. Three great principles of responsibility, seem naturally to follow this division.