THEY TOLD ME IF I VOTED FOR MITT ROMNEY, WE’D HAVE AN ANTI-SCIENCE GOVERNMENT THAT WOULD BRUTALIZE INNOCENT FOREIGNERS. AND THEY WERE RIGHT!

When the Justice Department arrested the chairman of Temple University’s physics department this spring and accused him of sharing sensitive American-made technology with China, prosecutors had what seemed like a damning piece of evidence: schematics of sophisticated laboratory equipment sent by the professor, Xi Xiaoxing, to scientists in China.

The schematics, prosecutors said, revealed the design of a device known as a pocket heater. The equipment is used in semiconductor research, and Dr. Xi had signed an agreement promising to keep its design a secret.

But months later, long after federal agents had led Dr. Xi away in handcuffs, independent experts discovered something wrong with the evidence at the heart of the Justice Department’s case: The blueprints were not for a pocket heater.

Faced with sworn statements from leading scientists, including an inventor of the pocket heater, the Justice Department on Friday afternoon dropped all charges against Dr. Xi, an American citizen.

It was an embarrassing acknowledgment that prosecutors and F.B.I. agents did not understand — and did not do enough to learn — the science at the heart of the case before bringing charges that jeopardized Dr. Xi’s career and left the impression that he was spying for China.

“I don’t expect them to understand everything I do,” Dr. Xi, 57, said in a telephone interview. “But the fact that they don’t consult with experts and then charge me? Put my family through all this? Damage my reputation? They shouldn’t do this. This is not a joke. This is not a game.”

It’s clown cars all the way down.