(CNN) -- A Pennsylvania court has struck down a controversial provision of a state law that stopped municipalities from controlling where natural gas companies could drill.
In a 4-3 decision, Pennsylvania's Commonwealth Court found that a portion of the state's Act 13 -- gas law revisions that were passed in February -- would require approval for drilling in all zoning districts, including limited residential areas.
The ruling Thursday restores the oversight municipalities had prior to Act 13, allowing them to regulate where natural gas drilling is permitted, said Jordan Yaeger, an attorney in the case.
Act 13 "was unprecedented regulation. It was a complete overreach," said Yaeger, who represented the township of Nockamixon and the Borough of Yardley, both in Bucks County near Philadelphia. They are two of seven municipalities that filed the petition.
The ruling is "a great victory," he said.
The municipalities involved sit above the Marcellus Shale, one of the largest natural gas deposits in the nation. It is found underneath parts of Pennsylvania, New York, West Virginia and Ohio. The natural gas reserve is attracting a flurry of gas companies wanting to drill.
Accessing the natural gas involves the controversial process of hydraulic fracturing, or "fracking."
The procedure involves pumping large amounts of water mixed with sand and chemicals into the shale formation thousands of feet underground under high pressure, fracturing the shale, which allows natural gas to flow freely.
There are concerns that the chemicals used in fracking have caused illnesses and gas leaks, and mix with tap water so that it can catch fire -- something covered extensively in media reports and in the Emmy-winning natural gas documentary "Gasland."
The Environmental Protection Agency is still studying the claims and is scheduled to release its findings in late 2012.
Allowing municipalities to have oversight on where companies can drill helps protect communities, Yaeger said.
"It keeps Pennsylvania from becoming a free-for-all," he said. "The gas industry thrived before this and they will continue to thrive."
Yaeger argued the law infringed on municipalities' due process rights by forcing them to rewrite their zoning codes to "create special carve-outs for the oil and gas industry," the ruling said.
"It would allow the proverbial 'pig in the parlor instead of the barnyard,'" wrote Dan Pellegrini, president judge, who penned the court's opinion.
Although Yeager anticipates the ruling will be appealed to the state Supreme Court, Nils Frederiksen, a spokesman for the Pennsylvania attorney general's office, simply said, "The ruling is under review."
Natural gas industry officials and advocates of drilling in the Marcellus Shale are in favor of the law because they want uniformity in rules governing where they can drill.
"The premise for the General Assembly's action earlier this year was to provide certainty and predictability that encourages investment and job creation across the commonwealth," Marcellus Shale Coalition President Kathryn Z. Klaber said in a prepared statement. "Lack of uniformity has long been an Achilles' heel for Pennsylvania and must be resolved if the commonwealth is to remain a leader in responsible American natural gas development and reap the associated economic, environmental and national security benefits."
On Wednesday, the EPA announced the agency completed its sampling of private drinking water wells in Dimock, Pennsylvania, where a group of residents, dubbed the "Carter 15," filed suit in November 2009 against Cabot Oil and Gas. They claimed the independent producer of natural gas, headquartered in Houston, contaminated their well water, court records show.
Despite finding hazardous substances, specifically arsenic, barium or manganese, all of which are also naturally occurring substances, in well water at five homes at levels that could present a health concern, the EPA determined that the levels of contaminants present would not require additional action by the agency.
"Our goal was to provide the Dimock community with complete and reliable information about the presence of contaminants in their drinking water and to determine whether further action was warranted to protect public health," EPA Regional Administrator Shawn M. Garvin said in a written statement. "The sampling and an evaluation of the particular circumstances at each home did not indicate levels of contaminants that would give EPA reason to take further action."