The Supreme Court’s decision to uphold the health care law is a major victory for millions of Americans who either can’t purchase health insurance or have chronic illnesses.

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About 50 million Americans are estimated not to have health insurance, about a sixth of whom are black. More than 30 million are estimated to get health insurance under this law, a disproportionate number of whom are black or Hispanic. Having insurance is generally associated with going to the doctor more and seeking preventive care, which can lead to fewer illnesses.

Also, currently when people change jobs or are laid off and seek health insurance, they often are told certain conditions won’t be covered by their health care plan. Or if they are unemployed, it is hard to buy insurance, because insurance companies charge much higher rates to people who are over 60 or have chronic illnesses like diabates.

Under the new law, insurance companies can’t charge higher rates to people based on age or health history. They can’t refuse to cover certain conditions of a person’s health.

In addition, the new law will eventually give tax credits based on income levels to people who want to purchase insurance. The subsidies vary in size, depending on their income level, but stop at about $44,000 per individual or about $88,000 for a family of four. More than 15 million people will get the tax credits, which go into effect in 2014.

Follow Perry Bacon Jr. on Twitter at @perrybaconjr