South Carolina wants to jam cell phone signals in prisons to prevent convicts from committing further crimes. There's one significant problem with the plan: It's against the law.

The struggle to stop cell phone use in prisons — where some experts say the devices have become a new form of cash — has states trying old-fashioned cell searches, sophisticated body scanners, even dogs trained to sniff out batteries and memory chips.

South Carolina's state prison chief, Jon Ozmint, wants to add to those tactics with existing technology that blocks cell signals.

Standing in his way is the federal Communications Act, which prevents states from using jammers or otherwise interfering with federal airwaves.

The Federal Communications Commission can give federal agencies the authority to use such jammers. But there's no such provision for state and local law enforcement.

"This is a classic example of a rule that has not kept up with technology," said Ozmint, who has managed South Carolina's 28 prisons for the past five years. "It's just hypocrisy beyond the pale of reason that the big bad federal government goes, 'Oh, well, we can use this technology, but you poor little states can't use the same technology to protect your citizens."'

Experts say the consequences of not using jammers can be dire. Perhaps the most glaring example took place in Maryland last summer, when Baltimore resident Carl Lackl identified a shooting suspect.

Authorities say the 38-year-old father was gunned down outside his home after the suspect used a cell phone to order the hit from behind bars.

In South Carolina, Ozmint blames illegal cell phones for most of the state's prison escapes. In one 2005 case, cell phones were found on two inmates who escaped a maximum security prison in Columbia by hiding in a trash truck.

In Texas this week, prison officials arrested the mother of a death row inmate on charges she paid for minutes on a cell phone that had been smuggled to her condemned son.

The inmate shared the phone with nine other inmates and called a state senator to say he knew the lawmaker's daughters' names, authorities said.

The governor's office said a corrections officer had been bribed to get the cell phone to the inmate.

John Moriarty, the Texas prison system's inspector general, said his team is investigating 700 incidents of smuggled cell phones among the state's nearly 160,000 prisoners — including one case in which officials have an X-ray of an inmate with a phone and charger inside his body.

In some places, inmates found with cell phones can have years tacked onto their sentences or have credit for good behavior taken away. And in several states, it's illegal for prison officials and visitors to give phones to inmates.

Such deterrence measures might become moot if officials could use the jammers to prevent unmonitored calls from ever happening within prison walls, as Ozmint hopes to do in South Carolina, in spite of everything it would take to give him that power.

"We have no authority to even grant it if we thought it was worthwhile or something that was warranted," said Robert Kenny, a spokesman for the FCC. "It's likely going to take some level of action by Congress."

Ozmint has invited federal officials and the state's congressional delegation to come to South Carolina's maximum-security Lieber Correctional Institution in a few months, where CellAntenna Corp., which manufactures jamming devices, will demonstrate that technology.

The devices prevent cell tower signals from ever reaching a phone, effectively blocking all calls. Jammers wouldn't block calls made from satellite phones, but those would be exponentially more expensive and cumbersome to smuggle into prison.

It's not clear how much it would cost to outfit South Carolina's prisons with the jammers, though officials say they'd focus first on installing the technology in maximum-security prisons.

Critics say it's impossible to contain the jamming technology to one or two buildings, and that using it runs the risk of affecting people using phones nearby.

"You can prevent emergency calls if these jammers are allowed," said Joe Farren, spokesman for CTIA-The Wireless Association, a trade group for the wireless industry. "You put signal jammers in, you interfere with critical communications, life and death."

That worry is shared by Zack Kendall, a security specialist for North Carolina's prison system, who said he doesn't know whether his prisons would take advantage of signal blocking because it could interfere with internal radio communications.

Howard Melamed, the chief executive of Coral Springs, Fla.-based CellAntenna, said signal jammers can be angled so that cell phones won't function inside prison walls, but someone standing just outside would have no problem making a call.

"It's no different than turning on a light and making sure the light doesn't spread outside of a certain area," Melamed said.

Ozmint said his officers are stretched thin by a rising prison population and tightening budget constraints. He believes the technology would help him run a safer, more efficient prison system.

"As long as you have human beings in prisons as inmates and employees, and as long as there are human beings on the outside of those prisons, you're going to have contraband in prison," Ozmint said. "This is a threat that can be absolutely eliminated."