Clients were understandably furious when Anthem Blue Cross, the largest for-profit health insurer in California, announced huge rate increases for people who buy their own insurance: an average increase of 25 percent, and a 35 percent to 39 percent rise for a quarter of the purchasers. The move also provided a textbook example of why the nation badly needs comprehensive health care reforms.

The reform bills stalled in Congress would put a brake on such out-of-scale premium increases by broadening the pools of insured people to keep average premiums low, by setting up competitive insurance exchanges and by starting to rein in the cost of medical care that is driving up premiums everywhere.

Private insurers in several other states also have sought and won double-digit increases for policies sold to individuals. In one striking case, a Blue Cross Blue Shield plan in Michigan sought a 56 percent average increase in premiums for individually bought policies but settled for 22 percent in a compromise with regulators.

If the increases go through in California, where regulators have limited powers to control rates, Anthem’s enrollees would have to choose between paying the higher price, moving to lower-cost policies, perhaps with a high deductible, switching to another insurer if they can find one to take them, or dropping coverage entirely.