malfeasance /mal-fēˈzəns/

1. Evil-doing, wrongdoing (rare)
2. An illegal deed, esp by an official (law)

• at the expense of
• at the feet of
• at the first blush
• at the fore
• at the full
• at the hand of
• at the hands of
• at the head of the poll
• at the heels of
• at the instance of
• at the latest
• at the least
• at the mercy of
• at the most
• at the outside
• at the point of
• at the ready
• at the risk of
• at the same time
• at the sharp end
• at the slope
• at the time
• at the top of one's voice
• at the top of the tree
• at the uptak