However, before signing BE SURE YOU KNOW HOW MUCH YOU WILL BE REQUIRED TO RE-PAY. The interest rates on such advances are usually very HIGH! Read the fine print!! Your lawyer can help you see if you really do want such a loan, even if the re-payment is quite expensive.
Some good news: most such loan agreements have a provision that if you do not win your case, you may not have to re-pay the loan. Again, read the "fine print" to see what you are obligated for before do the transaction.