HARRISBURG — A lawyer for Pennsylvania’s acting health secretary on Wednesday defended the validity of the secretary’s order requiring masks inside K-12 schools to fight COVID-19, asking state Supreme Court justices to focus on a single regulation.

“If this court finds that the masking order falls outside of that, then we lose,” Senior Deputy Attorney General Sean A. Kirkpatrick said during oral argument over a lawsuit seeking to invalidate the masking order.

The regulation, adopted in 2000, gives the Health Department authority to direct a “modified quarantine of contacts of a person” with a communicable disease or infection and any other control measures for the surveillance of disease needed to protect people from it.

Kirkpatrick said not allowing people inside K-12 schools amounts to a modified quarantine.

“Is there any legal authority for the proposition, even going back to the pandemic of 1918 or what have you, that ever equated masking with surveillance of disease under the statute?” asked Justice David Wecht.

Kirkpatrick said surveillance “only teaches you” about the disease, but that must be read along with the authority to impose disease control measures. “Those two have to go hand-in-hand or you don’t have control, you only have study,” Kirkpatrick said.

The justices have ordered that Acting Health Secretary Alison Beam’s directive, which took effect in early September and also applies to child care facilities, will remain in place while they consider a legal challenge from the state Senate’s highest ranking leader and others.

The masking order had been set to expire last Saturday under a 4-1 decision by Commonwealth Court that Beam lacked authority to require masks, did not follow state laws about enacting regulations and acted without a required existing disaster emergency declared by the governor in place.

The lower-court majority concluded Pennsylvania’s disease control law does not give health secretaries “the blanket authority to create new rules and regulations out of whole cloth, provided they are related in some way to the control of disease or can otherwise be characterized as disease control measures.”

Thomas E. Breth, representing the plaintiffs, urged the justices to focus on the legal meaning of surveillance, arguing that existing regulations do not empower Beam to issue the school masking order.

“The problem we have is when you go outside the existing regulatory process and you have one person that issues an order,” Breath said.

Breth represents Senate President Pro Tempore Jake Corman, R-Centre, who sued to challenge the mask mandate, along with fellow plaintiffs state Rep. Jesse Topper, R-Bedford, two religious schools, three public school districts and several parents of schoolchildren.

Beam’s actions, the litigants say, left the public unable to voice their opinions and the General Assembly unable to review the policy’s legality or necessity, as well as violated state law.

Kirkpatrick told the court he did not think there is anything to prevent schools and school districts from issuing their own masking orders, if Corman and the other plaintiffs win the case.

Democratic Gov. Tom Wolf, who installed Beam as acting health secretary, announced last month he intends to return authority over masking decisions to local school districts in January, but will continue to require masks in child care centers and early learning programs.