Why is the Department of Justice trying to drop corruption charges against New York City Mayor Eric Adams?

According to CBS News correspondent Scott McFarlane, the DOJ is making an unprecedented effort to drop corruption charges against Eric Adams based on political motives rather than legal merits. Their argument suggests President Biden wants Adams' help in New York City to support the president's border security policies. This rationale represents a significant departure from traditional justifications for dropping criminal cases, which typically involve changing facts or legal considerations. McFarlane characterizes this as a 'pure political motive,' highlighting how unusual this approach is in the justice system, as political considerations are not normally presented as legitimate grounds for dismissing criminal charges.