What is the "Common Fund Doctrine" and how is it relevant to my California personal injury settlement?

First, what is the "common fund doctrine?"  It first started with the

 United States Supreme Court when it created the common fund doctrine, as a source of attor­ney’s fees. If attorneys’ efforts create a 

fund or benefit for others (their own client), the court is empowered to award fees from that fund to the attorney.  This means if an attorney works to get you an injury settlement, then the private health insurance that covered the medical bills, who did not join in the efforts to obtain the settlement, must offset their reimbursement interests by the attorney contingency % the attorney charged on the injury case.  Thus lowering what the injured client has to pay back to the private health plan.  Make sense?  So a good lawyer can help their client save money by being able to not pay back dollar for dollar on  an health insurance lien. This is particularly true for Kaiser health plans.  A California injury lawyer can argue the common fund defense to lower what is paid back to Kaiser at time of settlement (Speial rules apply if Kaiser plan protected by ERISA).