A lien is when you are obligated to pay back money to your health insurance company when you recover money from a responsible party. If insurance does not pay for your medical treatment, you will not have a medical lien. When you receive health care, often it is because of your medical insurance, or medical insurance that you get through your work. The medical treatment you receive is determined by a contract between you and your insurance provider. In that contract, there usually is language that states if you recover money from any person who caused the accident, the medical insurance company can get their money back.
States have different rules about medical liens. California medical liens are limited to the amount that is actually paid by the insurance company. They can only get what is actually paid, not what is billed. Generally medical bills are an order of magnitude higher than what the insurance companies pay the hospital.
If you file a case, the law firm you hire will give notice to all possible lien claimants that a lawsuit has been filed. The law firm can also tell you the possible amount of the lien. The calculation that is used to determine the amount is the total amount of your paid medical bills reduced by the amount that the insurance company is entitled to be paid back. This amount is usually in the insurance contract, or set by state regulations.
Medical liens can be negotiated. The best types of law firms will negotiate your medical liens on your behalf. However, this is rare. You should ask any firm you are considering hiring, if they will negotiate medical liens for you after the case is resolved. Some firms charge for this, some do not.