Almost every client will ask if their spouse or partner will either have to pay their attorney's fees or whether they will be required to pay the other side's attorney's fees during their contested divorce, contested custody or child support case.
As a general rule in the US attorney's fees are not awarded to the "winning party". However, in matrimonial law the answer is not so clear. The NY Courts have long recognized that if one person has greater income and/or assets they should contribute to the lesser incomed or resourced spouse/partner to help "level the playing field". The idea is that family law cases should not be won or lost because one person has a lawyer and the other cannot afford an attorney. Of course, as with most legal issues, it is never quite as simple as that.
The matrimonial court has discretion in awarding attorney's fees and the results can vary significantly from one judge to the next. So while it might be relatively easy to predict when the disparity in income is significant, it is still subject to the Court's sense of fairness and review of why the legal fees were incurred if they are significantly larger then "usual". So if one person violates court orders that is a major factor. If one person hides assets that is a major factor. Another major factor is if one person needlessly delays the case thus requiring more court appearances or has failed to negotiate in good faith.
Just because there is a difference in incomes is also not a guarantee because if the difference is $25,000 there might not be an award. However, if the difference between the two persons' incomes is $100,000 or more the likelihood of a payment being ordered goes up significantly as long as the other examples of causing the larger legal fees do not exist.
This area of the law is extremely fact sensitive and nuanced. While I might tell a client that the odds are favorable of a judge awarding legal fees, the amount is much harder if not impossible to accurately predict. Retaining experienced matrimonial counsel with an excellent reputation with the Court is also a big help in a good outcome.