Does tax law ever enter into divorce?

Yes. Tax law and tax consequences enter into divorce, just as they do in every other aspect of life in the United States. Tax law can affect alimony and maintenance decisions, property settlement, child support, among other things. In order to make educated decisions in a divorce, a person should know enough about tax law and tax consequences to ask the right questions.
In tax law, the dumb question is the one that went unasked.

Moreover, the I.R.S. can and does examine the returns of formerly married couples who filed jointly. While formerly married couples are not responsible for taxes each owes after they are divorced, they remain responsible for taxes they owed together when they were married.