Bar exam hypothetical:  A two-lawyer, one-secretary firm is handling a malpractice case against a bankrupt hospital.  In September a key deadline in the matter—when claims must be filed to be recognized as pre-bankruptcy and therefore entitled to preferential treatment—is set for December 31. 

Also in September, Partner #1 receives word that his long-standing petition to adopt a child in China has been granted and he must fly over immediately.  He doesn't return until late November.  Meanwhile, Partner #2 is called up for active duty and departs for Iraq.  The secretary, alone in the office, goes into premature labor and is out on maternity leave from December through February.

The firm misses the deadline.  "Excusable neglect?"

No.