The core promise: no recovery, no fee
A contingency fee means the attorney's fee is contingent — dependent — on actually winning or settling the case. If there's no recovery at all, the client generally owes no attorney fee, regardless of how much work went into the case.
What the agreement is legally required to say
Illinois Rules of Professional Conduct require a contingent fee agreement to be in writing, and the agreement should disclose whether different fee percentages apply at different stages of the case — for example, a lower rate if the case settles before a lawsuit is filed, and a higher one if it goes to litigation.
Outside medical malpractice: a negotiated rate
For an ordinary personal injury claim — a car accident, a slip and fall — Illinois sets no statutory percentage at all. The rate is whatever the attorney and client agree to, with around one-third being the common market figure.
Inside medical malpractice: a real statutory ceiling
735 ILCS 5/2-1114 caps the contingent fee for a plaintiff's attorney in a medical malpractice case at 33⅓% of all sums recovered. Unlike the ordinary PI space, this is a hard statutory ceiling, not a private negotiation — an agreement above that rate simply isn't enforceable for the excess.
A specific rule for structured future payments
The statute addresses a detail unique to medical malpractice awards: when damages are paid out as future periodic installments rather than a single lump sum, that stream of payments must be reduced to its present value before the 33⅓% fee is calculated. This keeps the cap tied to the real economic value of the recovery, rather than the larger nominal sum of every future payment added together.