Consumers and insurers face new uncertainty with the Justice Department’s assertion this week that key provisions of the Affordable Care Act are invalid.

In a brief filed Thursday, the department asked a federal court to unwind the health law’s protections for individuals with existing medical conditions, such as diabetes or asthma. The law, known as Obamacare, prohibits insurers from refusing to sell coverage to people with pre-existing conditions or from charging them more than healthy consumers.

The brief was filed in a lawsuit brought by attorneys general that may take months to wind through the courts, and it isn’t clear what the outcome will be. Changes would create winners as well as losers. Meantime, insurers face new variables as they are deciding where to sell coverage and at what rates in 2019.

Health insurers warned of disruption to the market. “Removing those provisions will result in renewed uncertainty in the individual market, create a patchwork of requirements in the states, cause rates to go even higher for older Americans and sicker patients, and make it challenging to introduce products and rates for 2019,” America’s Health Insurance Plans, a trade group, said in a statement.

Here are four ways the case could affect health-insurance markets: