There were 60,000 Jews living in Krakow before the war, a quarter of the population; today, there are about 200. The Jewish district now feels at once like a tribute to and a caricature of what it used to be: Outside the Old Synagogue (Poland’s oldest), bright green trolleys advertising tours of Schindler’s factory bounce along the cobblestone. Near Remuh Synagogue and the Old Cemetery are kitschy, Jewish-looking restaurants with Hebrew signs and waiters offering picture menus to passers-by.

Whatever the sentiment, seeing “Heil Hitler” signs in the neighborhood was jarring. But the legality of it, I soon learned, is an ongoing debate.

Article 256 of the Polish criminal code states:

“Whoever publicly promotes a fascist or other totalitarian system of state or incites hatred based on national, ethnic, race or religious differences or for reason of lack of any religious denomination shall be subject to a fine, the penalty of restriction of liberty or the penalty of deprivation of liberty for up to two years.”

It continues:

“Whoever, in order to distribute, produces, records or brings, buys, stores, possesses, presents, transports or sends” the aforementioned items, or those with “fascist, communist or other totalitarian symbolism,” can be subject to that punishment.

But there’s a caveat: Violators are exempt “if the act was committed as part of artistic, educational, collecting or scientific activity.” Sales of antiques or collectibles with some historic, academic or artistic value are permitted; sales of recent reproductions are not.

It’s one of many ambiguities that makes the provision ineffective, according to Katarzyna du Vall, a lawyer in Krakow. “You don’t know who is an artist, educator, collector or researcher,” she said.

Another is the vocabulary. “The biggest problem from a legal perspective is what, exactly, ‘totalitarian state’ means,” Ms. du Vall said, explaining how contemporary scholars — political scientists, sociologists, lawyers and other experts — cannot agree on one binding definition.

“We talk about Article 256 a lot in Poland, and people don’t understand why those proceedings end up with nothing,” she said. “It’s really hard to enforce a law that is not clear for anybody — for judges, for those who punish, for those who commit those crimes.”

Rober Opas, a deputy chief of police in Warsaw, acknowledged the law and said violators would be punished. But “from our point of view,” he said in an email, “the problem is sporadic, and we do not receive many reports of this kind.” He also noted that it is the Polish court that determines the punishment for each perpetrator.