Ads for attorneys sometimes include something like "we don't get paid unless you win" as a way to explain their fee system. Most lawyers call it a "contingency fee."
The attorney's fee is based on the contingency or condition that your case wins at trial. If you win then the lawyer gets his fee. If not then he won't make a profit. These kinds of billing systems are common in personal injury cases and forbidden in certain legal areas, like divorce.
But just because the lawyer isn't profiting doesn't mean you get away without spending a dime.
When you pay your attorney, their fee isn't the only thing you're paying for.
Building a case also includes paying filing fees and other court-related expenses. It may also include the cost of any materials the attorney uses in preparing the case.
In a contingent fee arrangement, what you don't have to pay is the lawyer's hourly fee for the service they provide. That fee will come out of any winnings at trial or settlement.
Attorney fees are often expensive because lawyers provide a specialized service. The benefit to a contingent fee is that if you don't win, your costs are relatively low.
The downside is that attorneys are conservative about who they offer this fee deal to. After all, the attorney is doing a lot of work for you even if you don't win.
Not all cases will win, but an attorney should still fight for you until the end.
Because of the risk of not getting paid, attorneys generally offer contingency fee arrangements only if they think the case has a good chance of success. If it doesn't they may decline to take the case.
The relative cost of a contingency fee arrangement is low but it can still be a surprise if you don't know about the other potential costs besides attorney fees. If your attorney offers a contingency fee, be confident that while it may not be free, it will certainly be worth it.