Congress is rarely called upon to dispel conspiracy theories. But it needs to teach the Pentagon to separate fact from fiction, because American Jews are routinely denied security clearances based on nothing more than a fear that they are Israeli spies.

Consider Gershon Pincus, a 62-year-old dentist and lifelong New Yorker who sought a way to serve as he approached retirement. He found a position at a naval dental clinic in upstate Saratoga Springs, and started work in July 2014.

All was going well until this past September, when Pincus was informed that he wasn’t eligible for a security clearance. The rejection was accompanied by a Statement of Reasons that concluded “foreign contacts and interests may be a security concern due to divided loyalties.”

Incredibly, the totality of the concern about Pincus was his contact with his 89-year-old mother and his middle-aged brother and sister, who had moved to Israel as adults.

The charge of “divided loyalties” has a particularly repugnant resonance to American Jews. It’s usually whispered behind closed doors, and so it’s doubly disconcerting when it is the reason given for official government action.

What’s worse, the local military interviewer who conducted Pincus’ background check concluded that “there is nothing in his background or character that would make him vulnerable to blackmail, extortion, coercion or duress.” But an official at Office of Personnel Management headquarters in Fort Meade directed that Pincus be re-interviewed “to develop information related to potential Foreign Influence.”

When the second interviewer reached the same conclusion as the first, the military overruled their recommendations and denied Pincus’ request for a security clearance.

What is most alarming about this story is how common it is. We don’t know how often the military denies security clearances, but a database cataloging the appeals brought by employees of military contractors reveals that over the past decade there have been more than 100 appeals challenging clearances denied because of tenuous ties to Israel.

To appreciate how absurd this is, replace Israel with the name of another country also closely allied with the United States. Can you imagine a dentist being denied a clearance because his relatives had relocated to England, France, Germany, Italy or Spain?

The appeals database confirms that more denials are based on ties to Israel than to all of those countries combined. And when denials are challenged, they’re more likely to be reversed if arising from contacts with those countries.

Our military isn’t run by anti-Semites, and Pentagons run by both political parties have been equal offenders when it comes to Israel-based denials. So what’s going on here?

The answer is Jonathan Pollard.

Ever since Pollard pleaded guilty 30 years ago to spying on behalf of Israel, the military has been skeptical of American Jews with any connection to Israel. What disqualifies them is not anything they have done, but the ghost of Pollard.

The Pollard effect also explains the silence of our elected officials. Politicians were quick to criticize a candidate’s suggestion that Muslims be profiled, but not one has said a word about actual Pentagon policy that profiles and penalizes American Jews.

We challenged the denial of Pincus’ security clearance and won. The facts didn’t change, nor did Pentagon policy. But the military didn’t want to have to publicly defend the indefensible, and hoped to quiet the controversy by allowing a dentist to fix service members’ teeth.

But what about others?

The military will only change if Congress flexes its muscle. Sen. Kirsten Gillibrand had success in getting the military to address sexual assault. She and Sen. Chuck Schumer, together with New York’s congressional delegation, should press the Pentagon to overhaul its clearance policies.

For too long, the military has used the shield of secrecy to shroud its security-review policies. Congress needs to remind the Pentagon that holding a large group of people responsible for the conduct of someone else they look similar to is the definition of stereotyping, not an excuse for it.

Avi Schick, a partner at Dentons, previously served as deputy attorney general of New York.