On One's Watch Meaning
(chiefly US, idiomatic) During the period of time when one is in a position of authority or responsibility.
Example: 1991, Michael Duffy, "The CIA: See No Evil, Hear No Evil," Time, 30 Sep.:
Gates emerged from the first week of hearings bearing only a few scratches. . . . He even vowed to resign if illegal activity occurred on his watch.
2005, Amy Silvers, "100 miles per hour for 102 years," Milwaukee Journal Sentinal, 19 Feb.:
Woods dismissed the idea that anyone could get away with election fraud on her watch.