The spreading violence of the drug wars along the Mexican border may have one unintended consequence. It could upend efforts to curb illegal immigrants by giving Mexican border-crossers a tool they never had before: a valid claim for political asylum.

For decades, immigrants coming from Mexico were denied asylum because Mexico was a stable and relatively peaceful democracy. But that is changing now.

Last week, at least 30 Mexicans from the town of El Porvenir walked to the border crossing post at Fort Hancock, Texas, and asked for political asylum. Ordinarily, their claim would be denied as groundless, and they would be turned back. Instead, they were taken to El Paso, where they expect to have their cases heard.

No one doubts that they have a strong claim. Their town on the Mexican side of the border is under siege by one or more drug cartels battling for control of the key border crossing. According to Mike Doyle, the chief deputy sheriff of Hudspeth County, Texas, one of the cartels has ordered all residents of the town of 10,000 to abandon the city within the next month.

"They came in and put up a sign in the plaza telling everyone to leave or pay with their own blood," Doyle said. Since then there has been a steady stream of El Porvenir residents seeking safety on the American side of the border, both legally and illegally. Among them are the 30 who are seeking political asylum.

In recent days the situation in the impoverished, dusty border town has grown worse. According to Jose Franco, the superintendent of schools in Fort Hancock, the cartels have threatened to execute children in school unless parents pay 5000 pesos in protection money.

And on Wednesday night, according to Doyle, several houses in El Porvenir were set on fire, and there were reports of cars loaded with furniture leaving the town.

Authorities fear that an incident might spark a mass exodus by the residents of El Porvenir that might cause them all to surge across the border at once.

Doyle says there are no plans yet to set up camps for an influx of refugees. "There is just no way to plan for that," he said. "We are waiting to see what happens. We will use the standard natural disaster procedures if it happens -- the Red Cross and housing at the schools, and if it gets worse, the state and the federal government will have to step in."

If political asylum is granted and made available to a large section of the Mexican population, immigration experts say, it could have implications far beyond El Porvenir. They say it could open the floodgates for a new wave of immigration from Mexico, much as allowing Chinese to seek political asylum because of China's one-child policy created a huge migration when it happened. After that ruling, tens of thousands of Chinese boarded boats and planes and told immigration officials they were seeking asylum because they were allowed to have only one child. Most were granted immigration papers and allowed to stay. Even those who made spurious claims were granted a hearing and often simply disappeared.

According to Will Matthews, an American Civil Liberties Union spokesman, the wall that has kept Mexicans from requesting political asylum has already cracked. He says that a decision by Board of Immigration Appeals (BIA) to send an police informant, Guillermo Eduardo Ramirez-Peyro, back to Mexico was overturned by the federal Eighth Circuit Court of Appeals, which found that asylum could be granted to him and others based on the Convention Against Torture.

"The court said that under the convention, 'acquiescence by government officials that could lead to a petitioner's harm' was grounds to grant political asylum," he said. The court, however, did not grant asylum; it ordered the BIA to rehear the case. Last week, after five years, the BIA reversed course and granted Ramirez-Peyro political asylum.

According to Shuya Ohno of Reform Immigration for America, even if hundreds or thousands of Mexicans sought asylum because of the drug wars, it is not likely that many would get it. "It is a hard case to make and very few succeed," he said. "Often it requires that those committing repression or threatening harm admit to it."

However, he said, it is likely if that if thousands of Mexicans made the claim, "it would stress the system incredibly" as well as delay their deportations. He said that the immigration court system is already overloaded and often staffed by volunteers just to keep it moving, and that if it was flooded with asylum claims it would be in danger of failing.

Ira Mehlman of the Federation for American Immigration Reform (FAIR) said the situation was troubling. "The entire system of political asylum claims was set up for a different era," he said. "It was to protect people from repressive governments but now is being used when there is just a general breakdown of order."

He said that making a political asylum claim available to Mexicans along the border could result in a swamping of the already overloaded system and bring it to a grinding halt. "Once an avenue of appeal is opened, then it will become used" he said. And not just by those who qualify, but by thousands who don't.