A militant subgroup within a labor union has organized in protest over what it feels are critical questions of worker safety. When their initial attempts to bring their concerns to management arc rebuffed, they walk out in a wildcat strike. Some other rank-and-file union members, who are not particularly affected by the safety rules in question, nevertheless support the strike because they think the strikers' concerns should be addressed by management. The strikers present a series of safety demands to managementif these demands are met, the strikers will return to work. Management agrees to meet the demands, and the strike ends. Management then immediately fires all the wildcatters for participating in the illegal strike and takes no action on the safety issues. The union leadership accuses management of unethical negotiating.

Question

Please explain the meaning of "duty ethics" from this case.