The arrangements generally do not run afoul of the law and have not been condemned by legal or medical groups as unethical. However, civil defense attorneys complain that they lead to higher litigation costs.

For those without insurance, the appeal of a lien agreement is obvious: they can get treatment that they otherwise wouldn't be able to pay for. Lien doctors may also provide services that would not be covered through insurance.

However, plaintiffs attorneys also have an incentive to direct clients to lien doctors, even if the client already has good insurance.

The incentive is due to the fact that a big part of what determines personal injury judgments and settlements is the price of the plaintiff's medical bills. If the plaintiff can present the rates charged by the doctor, rather than the typically much-lower rates negotiated by an insurer, the overall judgement or settlement will be greater, which results in a larger contingency payment for the attorney.

"This is totally to enhance the bank accounts of the plaintiffs' lawyers," Anthony Kohrs, a civil defense attorney in Los Angeles, tells the Wall Street Journal.

The arrangement obviously does not end up working out for well for patients who do not succeed in their litigation. While unsuccessful plaintiffs rarely have to pay their attorneys, who work on a contingency basis, most lien doctors insist on getting paid no matter how the lawsuit is resolved.

In many cases, the Wall Street Journal reports, the patients end up negotiating a reduced payment with their doctors.

Read more: 

• Uncompensated care costs at hospitals on the rise
• Physician group purchases drive up health system prices
• Who are America's uninsured?