THE exchange of information in a divorce, related to the respective economic, financial, and personal situations -- including the extent of the property ownership, debt, and income, is part of the discovery process in litigation. Even if a case is not going to trial, the parties are entitled to know the extent of the assets, debts, property, financial transactions, etc.
The exchange of this information is known as the "discovery" process generally, and there are very specific rules that apply to specific applications. If assets are hidden or never disclosed, if debts are amassed and never disclosed, if someone won a lotto and never disclosed it, or any type of financial gain or big loss that was kept hidden, the other spouse should know about it.
In California, there has been ongoing case law dealing with financial issues where one spouse basically gets left out of the loop and doesn't know the full scope of what was going on (non disclosure)...
and when that kept happening, the Courts finally realized that "non disclosure" was the center of many cases going to appeal.
New laws were passed to change the Family Code so that declarations of disclosure are done properly to help each litigant know their financial picture.
For example, if a wife did not realize to what extent her husband had in terms of a trust funded by community assets, or stock purchased with community earnings (earned during marriage, and not from separate property) or a business that was set up with community earnings, and operated online such as an adult x rated venue, which takes in money online from credit cards--you get the picture. Or maybe the husband was paying support to an unknown child father outside of wedlock for 10 years.
Depending on the case, many scenarios can have mixed facts, and not all cases will be alike. In fact, it takes years of working in Family Law to really see how bad things can get, especially if one party files bankruptcy and the other one does not. Fortunately, the bankruptcy rules help the spouse who has been shafted, for the most part, especially if fees relate to spousal support.