Is it permissible not to pay Zakat on money because of the need for expenses for a lawsuit?

If you have legal debts, even if deferred, or zakat debts, or a wife's mahr (dowry), and so on, then the zakat is waived for you from that amount equivalent to those debts, provided you do not possess other wealth that is not subject to zakat which could cover them. However, if "expenses" means that you will spend the money without it being a debt, then that does not waive anything from the zakat. What we have mentioned is specific to zakat on cash (ayn). As for zakat on livestock, crops, and minerals, it is not waived by debt.