"My legal recommendation to them would be to keep that dog completely isolated or away from anyone because he’s a known danger," said Cooper, chairman of D.C.-based Cooper Law Partners. "I believe it’s their duty to protect people from their dog."
First lady Jill Biden’s press secretary Michael de Rosa confirmed the "nip" in a statement to Fox News: "Major is still adjusting to his new surroundings and he nipped someone while on a walk. Out of an abundance of caution, the individual was seen by WHMU and then returned to work without injury."
The encounter took place on the White House South Lawn Monday. CNN first reported the bite, adding that the employee worked for the National Park Service.
Cooper told Fox News that an overwhelming environment like the White House is not a "legal defense that would carry any weight" in court.
Washington, D.C., law is strict on dog owners who know their dog has had at least one biting incident in the past.
"The one feature of Washington, D.C. dog bite law, and it’s relevant to the Major Biden story, it’s called the one-bite rule," Cooper said. "If the dog bites someone after it has already shown that it will bite someone, then there is presumed negligence on the owner of the dog."
D.C. law defines a "potentially dangerous dog" as a dog that "without provocation, chases or menaces a person or domestic animal in an aggressive manner, causing an injury to a person or domestic animal that is less severe than a serious injury." Dangerous dogs can be put down by the city under certain circumstances.
Monday’s incident was the second time Major bit someone at the White House in less than a month. On March 8, Major sank his teeth into a Secret Service employee, who also required attention from the White House medical unit. White House Press Secretary Jen Psaki referred to that incident as "minor."
If either bite had been more serious, the Biden family's insurance policies could have come into play, Cooper said.
"Typically homeowners insurance covers dog bite injury, and it’s weird — I don't know what kind of homeowners insurance comes with the White House," he said.
Of course, one thing sets this dog bite story apart from the rest: the dog's owner is the president and enjoys special forms of legal immunity.
"No one can prosecute the president for a dog bite or anything else," Stephen Caramenico of Malloy Law Offices told Fox News. "It comes down to just being a competent dog owner because you do have something that has the ability to harm people, so how do you control that animal, who do you let them around?"
Large dogs can be dangerous like firearms or vehicles, Caramenico said.
"I do know that German Shepherds are very powerful dogs. That’s why they use them in military and police situations," he said. "They’re very loyal dogs."
Major is the first rescue dog to have the run of the White House but was sent back to the Biden family home in Wilmington, Del., after the first bite. The president and first lady adopted him from the Delaware Humane Association in 2018.
Fox News' Morgan Phillips contributed to this report.