The panel of appellate judges who will decide whether Helis Oil & Gas Co. can drill its controversial “fracking” well in St. Tammany Parish — a project on hold since April — left all parties in suspense Thursday after grilling both sides with skeptical questions during a half-hour hearing in Baton Rouge.

On the one side, attorneys for Helis and the state’s Office of Conservation were asked whether their position meant that local government should be entirely powerless to block such projects.

On the other side, attorneys for those who oppose the well — including St. Tammany Parish and the group Concerned Citizens of St. Tammany — were asked if the parish should be allowed to effectively ban all oil drilling within its jurisdiction.

That tension — the struggle over who has the power to say where wells are drilled — dominated the hearing and, at times, put lawyers for both sides on the back foot.

The hearing before the state’s 1st Circuit Court of Appeal was the result of a ruling by 19th Judicial District Judge William Morvant, of Baton Rouge, who said in April that parish zoning laws could not be used to prevent Helis from using its state-issued drilling permit at the site just off La. 1088 northeast of Mandeville.

Even though Morvant ruled in favor of state regulators and the oil company, he allowed the parish to file a suspensive appeal, one that sets aside his ruling while it is appealed. So, for now, the half-finished drilling site sits idle while the case works its way through the courts.

On Thursday, Judges Guy Holdridge and John Michael Guidry took turns quizzing both sides about what their arguments might mean for state law. Judge Ray Chutz remained mostly silent.

“You’re saying that a parish can control where a well can be drilled?” Holdridge asked Carl Conrad, who represented the parish.

“Yes,” Conrad replied, arguing that parish zoning laws must be deferred to in issuing drilling permits. Because the wooded site where Helis wants to drill is zoned residential, the parish says an industrial project, such as a drilling well, should not be permitted there.

Later, Holdridge asked Conrad if parishes could band together to ban fracking wells throughout the state by use of zoning laws, effectively barring any new wells in Louisiana.

“Where, in St. Tammany Parish, can you drill?” Holdridge asked Conrad, who replied that it would be permissible in areas zoned for industrial use.

Matt Jones, a lawyer for Helis who argued that state law prohibits the parish from interfering with the state’s role as regulator of oil and gas drilling, faced a similar interrogation.

“You could drill on the 50-yard line of Tiger Stadium, on the eye of the tiger?” Guidry asked.

“Yes,” Jones said, but he added that it couldn’t happen without the landowner’s consent.

“The way higher ed (funding) has been cut,” that might happen, Guidry joked to a ripple of laughter.

Guidry said Jones made it sound as if zoning was irrelevant in drilling decisions. “Under your argument, local government doesn’t really have any say,” Guidry said.

Holdridge also wondered why the parish and CCST did not challenge the permit by asking for a judicial review, as the town of Abita Springs did. Earlier this year, District Judge Timothy Kelley, also in Baton Rouge, ordered the Office of Conservation to prove it had taken Abita Springs’ concerns into account. The office reissued the permit — with some additional documentation — a few months later.

“The citizens and zoning have to be taken into consideration here,” Holdridge said. “I don’t know if that was done.”

As is typical, the appellate court did not issue a ruling Thursday. Whichever way it decides, the case is likely headed for the state Supreme Court.

Another legal challenge to the well is taking place in federal court, where Abita Springs has challenged the drilling company’s Army Corps of Engineers wetlands permit.

The proposed well near Lakeshore High School has been controversial since the first plans became public in April 2014. Helis wants to dig a 13,000-foot vertical well and then use hydraulic fracturing, or fracking, to extract oil at the southeastern tip of an underground rock formation called the Tuscaloosa Marine Shale.

Fracking is a controversial practice by which water, sand and other chemicals are injected at high pressure into a horizontal shaft. That mixture creates tiny cracks in rock through which the oil or natural gas can be extracted.

Follow Faimon A. Roberts III on Twitter, @faimon.