Which of the two is more likely to pay a legitimate health insurance claim -- a private insurer or Medicare.

The answer is Medicare. How do we know? The private insurers said so.

Executives of three large health insurers audaciously told a House committee that they would continue cancelling medical coverage for sick policyholders. The three companies -- Wellpoint. Inc., UnitedHealth Group and Assurant, Inc. -- have reaped a bonanza of $300 million by cancelling coverage of more than 20,000 people over the past five years.

The cancellations go well beyond applicants who intentionally lie or commit fraud on their insurance applications. One woman told Congress her policy was rescinded after she was diagnosed for breast cancer. The reason? She failed to disclose treatment for acne. The sister of an Illinois man said her brother, who died of lymphoma, had his policy rescinded for failing to report a pair of unrelated illnesses that a doctor had noted on a chart but didn’t discuss with the patient. The problem is compounded by insurance company executives who actively encourage the denial of claims. Performance reviews show that Blue Cross executives praised employees who rescinded policies, and Health Net, Inc. actually paid “rescission bonuses.”

Rescissions aren’t isolated horror stories. In 2007, the California Insurance Commissioner identified 1,262 “serious violations” by Blue Shield alone over a four-year period. No wonder that three-fourths of all medical bankruptcies involve families who had what can only be loosely described as “health insurance.”

This is the system that opponents of a public option want to preserve? At least “government-run” health care -- Medicare, Medicaid and the Veterans Administration -- pays its claims (how many veterans would give up their public option?). Given the performance of private insurance carriers, how can anyone claim that the private system is ready to offer more reliable care than a public alternative that’s based on treatment rather than rewarding executives and satisfying stockholders?

When it comes to the individual health insurance market, the private sector has failed, and its representatives have told Congress it has no plans to change. That, all by itself, is a compelling argument for a public health insurance plan.