HARRISBURG — A Commonwealth Court judge on Friday denied requests by top Republican legislators and the gas-drilling industry to participate in a lawsuit challenging the state’s Marcellus Shale law.

Senior Judge Keith B. Quigley wrote in his order that Senate President Pro Tem Joe Scarnati and House Speaker Sam Smith do not have a “legally enforceable interest” in defending the intent behind the law. He wrote that the interests of a collection of industry trade associations and companies will be represented as the state defends the constitutionality of the law.

Officials from seven municipalities, along with a Monroe-ville doctor and the Delaware Riverkeepers Network, argue in their lawsuit that aspects of the law restricting how they craft zoning rules for gas drillers will keep them from adequately protecting residents. Last week, Judge Quigley granted a 120-day stay on that portion of the law.

The remainder of the law went into effect a week ago.

Jordan Yeager, an attorney representing the municipalities, said his clients are pleased the judge denied the requests to intervene.

“The only legitimate interest in the case on that side of things is to defend the constitutionality of the act,” he said. “The attorney general can do that just fine.”

Drew Crompton, chief of staff to Mr. Scarnati, said the legislators will discuss how to proceed.

“Judge Quigley ignored at least seven similar previous cases where the legislative leaders were granted intervener status,” he said. “This is the first time ever that we know of that this request was not routinely granted by the Court.”

A spokesman for the Marcellus Shale Coalition said the group is disappointed in the decision and reviewing what to do next.

In his order, Judge Quigley also gave an expedited timeline for the case, with deadlines for filings in April and May.

Karen Langley: klangley@post-gazette.com or 717-787-2141.