Such efforts stretch back to the 1990s, and after numerous congressional hearings and bills, they have left a patchwork of incomplete, overlapping laws, contradictory court rulings and overall uncertainty about how much power the Food and Drug Administration has to regulate compounders.

And with a gridlocked Congress at its most unproductive in decades, experts don't expect to see new laws passed anytime soon.

The issue flared up in the past several days after the New England Compounding Center of Framingham, Mass., came under suspicion as the source of the tainted steroid shots that have sickened 169 people in 11 states, causing 14 deaths.

Several members of Congress this week promised to introduce legislation giving the FDA greater authority to oversee the specialty pharmacies, which custom-mix drugs for patients for everything from menopause symptoms to cancer. The compounding industry in the U.S. has grown into a $3 billion business with 7,500 pharmacies, according to its trade group.

"It's incredibly complicated to explain what our authority is and is not, and the nuances of that," Deborah Autor, FDA's deputy regulatory commissioner, said Thursday. She suggested the FDA would support new laws to oversee the industry.

"The world has changed a lot since the days of mortar and pestle, and this is the time for pharmacists, for lawmakers, for regulators and for doctors to sit down to grapple with this new model of pharmacy compounding," Autor said.

Compounding pharmacies are critical for patients who need solutions, creams and other medicines customized for, say, smaller dosages or to remove ingredients that cause allergies. Unlike drugs that are manufactured for mass-market distribution, these products are not subject to premarket review by the FDA.

All pharmacies, including compounding pharmacies, have long been regulated by state pharmacy boards, many of which date back to the 19th century. At that time nearly all drugs dispensed in the U.S. were individually compounded by pharmacists. The law that created the FDA in 1938 gave the agency strict authority over drug manufacturers, which quickly eclipsed pharmacists as the main producers of prescription medicines.

For decades, the state-federal divide persisted, with states overseeing compounding pharmacies and the FDA policing drug manufacturers.

But in the 1990s, FDA regulators began to more closely scrutinize compounding pharmacies, as their number multiplied and some grew into big businesses. Instead of making individualized products based on a physician's prescription, companies began mass-producing products and promoting them broadly.

"When you get into that situation, pharmacy compounding can be a disguise for unregulated manufacturing," said Michael Labson, a food and drug attorney in Washington. Recent drug shortages caused by consolidation among drug manufacturers, among other factors, have only increased demand for compounded alternatives.

In recent years some compounding pharmacies have been blamed for outbreaks caused by contaminated medicines. Two people were blinded in Washington in 2005. Three died in Virginia in 2006 and three more in Oregon the following year. Twenty-one polo horses died in Florida in 2009. Earlier this year, 33 people in seven states developed fungal eye infections.

Compounding experts, including the president of the leading compounding pharmacy trade group, believe the New England Compounding Center crossed the line into full-scale manufacturing. Indeed, the FDA had warned the company in 2006 about compounding and distributing anesthetic "for general distribution" rather than for individual prescriptions.

FDA officials said they followed up with the company after sending the warning letter but did not re-inspect it.

"They assured us they were adequately protecting patients and complying with applicable laws and regulations," Autor said. "We took some action, but it's very complicated — our ability to take action here."

A spokesman for New England Compounding Center had no comment.

FDA officials have repeatedly stressed the challenges the agency faces policing compounding operations. In fact, some former agency officials say that the FDA is hesitant to act after years of legal battles with lawyers and lobbyists for the industry.

The International Academy of Compounding Pharmacists has spent more than $1 million lobbying Congress in the past decade and has a track record of defeating measures opposed by the industry. A 2003 measure to set up an FDA advisory committee to oversee compounders was killed by then-House Majority Leader Tom Delay, who said it would create unnecessary federal interference. Delay represented Sugar Land, Texas, the headquarters of the compounding academy.

The academy did not immediately return calls for comment Friday.

Even when the FDA has succeeded in getting legislation through Congress, it has gotten tangled up in the courts. In 1997 Congress passed an FDA-supported law that allowed the agency to regulate compounding pharmacies if they overstep certain standards for drug production, labeling and advertising. Specifically, the law said that compounding pharmacies were subject to FDA oversight if they advertised their products.

A federal appeals court sided with pharmacists and ruled that this last requirement was unconstitutional, and the Supreme Court upheld the decision in 2002. But the court did not rule on whether the other requirements in the law should stand, creating a legal limbo for regulators. Since then, different appeals courts have issued conflicting judgments on the remainder of the law, which could wind up back at the Supreme Court.

Still, some former agency lawyers say new laws are not necessary when dealing with companies that have clearly crossed the line from compounding drugs to full-blown manufacturing.

"Legislation isn't necessary here," said Sheldon Bradshaw, former FDA chief counsel during the Bush administration and now an attorney in Washington. "FDA already has all the authority they need to go after the New England Compounding Centers of the world. I'm honestly shocked by how FDA is now downplaying its authority in this regard."