The Senate health-care legislative draft — officially titled the Better Care Reconciliation Act of 2017 — will, if passed, represent the greatest policy achievement by a Republican Congress in generations.

For decades, free-market health-reform advocates have argued that the single best idea for improving U.S. health care is to maximize the number of Americans who can afford to buy health insurance for themselves, instead of having to depend on the government or their employer. The Senate bill transforms the American health insurance landscape in this direction.

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The Senate proposal wouldn’t cut Medicaid spending in real dollars — spending would continue to grow — but it would slow the rate of spending for the program, phase out extra money the federal government has given to states that expanded Medicaid under the Affordable Care Act (also known as Obamacare) and leave states to pick up more of the tab.

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Health insurance cannot really be insurance because human health is un-insurable: human beings are not machines or buildings whose function or condition can be ascertained objectively. Yet, an objective assessment of damages and costs is essential for any contractual arrangement to function in a sustainable manner.

Consider, for example, that medical care is based on the legal principle of “medical necessity.” Medical necessity is invoked when, presumably, there is an impairment in the patient’s health that could be remedied by a medical intervention. But medical necessity is a perniciously elastic concept that cannot possibly satisfy the precise contractual requirements of insurance.

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