> In Gartenlaub’s case, the government made sealed filings, so neither the defense nor the public was able to see them. Based on the secret filings, the judge held that the government had shown probable cause that the house to be searched belonged to “an agent of a foreign power." That's typically what you read about foreign police states.
It is, but isn't it also the case that secret court filings are as old as the US courts? How else would espionage prosecutions work? Similarly, how would complicated organized crime investigations work without secrecy? Isn't the alternative that prosecutors get exactly one bite at the apple, and if they're wrong, the target of the investigation is tipped off? The case that ultimately appears before the court, of cour…
In counter-espionage cases, it is very common for the government to balance concern about disclosing its methods with likelihood of a conviction. If they fuck up the investigation and tip off the target before the trial, or tip off other targets during the trial, it's not the court's job to give them a do-over.