The future of U.S. President Barack Obama's healthcare reform has been put in doubt after a judge ruled unconstitutional a key element obliging people to buy health insurance.

The judge in Virginia ruled on Monday said the federal government cannot require someone to buy health insurance. Nearly half the states have filed lawsuits challenging the healthcare reform law and Republican governors and state legislators are working to stall the plan's implementation.

In Congress, Republican lawmakers have pledged to repeal the law once they take control of the House of Representatives in January.

Here are some questions and answers about healthcare reform's future after the judge's ruling:

What Happens Next In The Courts?
This week, a federal court in Florida will hear a lawsuit filed by 20 states opposing the plan on much the same grounds as Virginia's: that requiring people to buy health insurance goes beyond the reach of the Commerce Clause of the Constitution that grants the federal government authority to regulate commerce between states.

Constitutional scholars expect one of the two dozen lawsuits filed since the law was enacted to reach the Supreme Court, most likely the multistate lawsuit or Virginia's.

While Virginia's attorney general is trying to accelerate the appeals process for the lawsuit, with some Republicans that it go immediately to the Supreme Court, it will likely not reach the highest court in the country for a year.

A federal court in California has also dismissed a lawsuit, which is now before the 9th U.S. Circuit Court of Appeals, that said the healthcare law violates individual rights, increases taxes, and violates physician-patient privileges, along with violating the Commerce Clause.

On Tuesday, U.S. Attorney General Eric Holder and Health Secretary Kathleen Sebelius published an editorial saying they "are confident that the law will ultimately be upheld."

Will Congress Repeal The Whole Law?
Republicans took control of the House of Representatives in elections last month, but not the Senate. While party leadership has said they will work toward a full repeal, it will be easier for Republicans to chip away at parts of the law such as the individual mandate, given the opposition they will face in the Senate. Obama has said he would veto any bill repealing parts of the healthcare law. Republicans can try to withhold money needed to administer and enforce the law. But, again, they would need control of both chambers of Congress to pass such measures.

Senior White House officials say they have yet to see proposed legislation on repealing the law or parts, and they are not in talks with lawmakers to change any of it.

How Else Can States Affect Healthcare's Future?
Many of the provisions in the healthcare law were given to the states to implement, which has set them scrambling to start new programs or expand existing ones at a time when revenues are low and some are unable to meet basic spending pressures. Only a few provisions gave them funds to hire additional staff or change computer systems. Adding to the confusion is the process under which the law made it out of Congress, known as reconciliation, which required lawmakers to use an early draft of the bill. By the time the law was signed, many of the legislated deadlines states had to meet had already passed.

Some states have already decided not to establish or run health insurance exchanges, an open market where individuals can buy insurance. Others are putting off expanding Medicaid, the healthcare program for the poor run by the states with federal reimbursements. Outgoing Minnesota Governor Tim Pawlenty, a leader in the Republican Party, and others have issued statewide orders to only implement parts of the plan that are mandatory and not to participate in the optional programs.

Will Obama Put The Plan On Hold During Court Process?
Senior White House officials said after the Virginia ruling that Obama will continue implementing the plan while the court challenges play out. The administration has time to do both because the part of the law ruled unconstitutional, known as the individual mandate, will not come on line until 2014. Already, provisions allowing states to review increases in health insurance premiums and sending money to community health centers have moved forward.