What liabilities are involved with divorce and why?

Great question, because you are right, the concept of fairness should always be considered in divorce actions. Many areas of the law come into play when divorces are filed and litigated. Always remember that the debt/liability contracts that existed before the divorce was filed still must be considered and be dealt with during and after the divorce. In your car loan example, the car loan company can pursue any party or parties who signed the loan contract, because the loan company did not grant credit conditioned on the parties staying married. In most jurisdictions, the divorce court can order one or both divorcing parties to actually make the loan payments, but the loan company can still pursue one or both of the parties who signed the loan contract if the payments are not made. The situation can get even more complicated when bankruptcy is involved. Generally, the divorce court will not make financial decisions based on who filed the divorce, because there are too many reasons (good or bad) why one party may or may not have decided to be the one who files.