What began as your run-of-the-mill inflatable rat situation outside a Center City hotel and restaurant last summer could change how unions protest.

Building trades unions have long used the inflatable rat, known to some as Scabby, and other inflatable animals to protest projects using non-union contractors.

But when Electricians Local 98 used rats to protest a new hotel and restaurant in Center City in 2018, owners complained it violated federal labor law by harassing a secondary employer — that is, a business that’s not the contractor with whom the union has a dispute.

The case has since become the center of an effort to outlaw the rat, which National Labor Relations Board general counsel Peter Robb, a Trump administration appointee, says is so threatening that it’s “tantamount” to coercion. Now it’s in the hands of the Republican-controlled board.

This week, Local 98, whose leadership is facing federal charges of embezzlement, bribery, and theft, filed a response to the NLRB.

The question being raised in reams of legalese verges on the absurd: Exactly how threatening is Scabby the Rat? Is it truly a menace? Or is it, as business manager John J. “Johnny Doc” Dougherty put it, just a harmless balloon? “No different,” he said in a statement, “than ones used in holiday parades and children’s birthday parties.”

But a larger question has broader implications: Should the government be able to dictate how unions protest?

Last month, a New York judge upheld a union’s right to use the rats outside of several Staten Island ShopRite groceries, saying it would “raise serious constitutional concerns" to stop them.

The original protest took place in Philly in July 2018, not long after the old Parker-Spruce hotel gave way to the Fairfield Inn and Libertine restaurant on 13th Street.

The scene outside the Fairfield: Two inflatable rats, standing eight feet tall near the hotel entrance, and a group of Local 98 members passing out fliers shaming property developer the Wankawala Organization — as “greedy pigs” — for hiring nonunion contractors.

What passersby saw depends on who you ask.

“The rat, which had red eyes, sharp black extended claws, and a scabby stomach, towered over the windows of the Libertine and anyone who happened to be near it," wrote a lawyer in a brief for the NLRB’s general counsel. It was “huge,” “menacing,” and “hostile-looking.”

But the judge who heard the case, Robert Giannasi, noted upon viewing a three-hour video of the rat occupation: “Most pedestrians walked right by the rat without even pausing to look at it.”

(Welcome to Philadelphia.)

Giannasi ruled in May that Local 98 didn’t break the law with its rats. Robb and the owners of the Fairfield, Shree Sai Siddhi Spruce LLC, appealed.

The NLRB’s decision could take months.