In wronging their brother, Joseph's ten brothers took advantage of failed leadership.
Jacob (Israel) was the head of the family. But Jacob had unfairly favored Joseph, and besides, he wasn't around.
Reuben, a man who excelled in strength and dignity, was unstable as water. Despite being the oldest brother, despite having enough responsibility to try to rescue Joseph, and despite being Godly enough to know that this was wrong, Reuben did not command enough respect to accomplish what was right.
Judah, a strong, courageous leader, rallied his brothers to do wrong, and he got away with it... for a long time.