I'm not sure if this is an exact legal expression, but the term "minor fraud" would probably fit the meaning of the kanji quite well.

I couldn't find "jun-sagizai" in any of my dictionaries, but the Dictionary of Anglo-American Law (Ei-Bei hoo jiten edited by Tanaka Hideo) lists "quasi-crime" as "jun-hanzai" so it's close, anyway.

"Exists where conduct, though not actually fraudulent, has all actual consequences and all legal effects of actual fraud." (Black's Law Dictionary)
The prefix jun- is commonly used for "constructive" in this sense.

At first I was leaning toward the more literal "quasi-fraudulent [activities, etc.]" but then I saw Dasitkin's comments on "constructive fraud," with which I tend to agree, even for formal legal contexts. My hesitation with "constructive" was partly due to the fact that Dictionary of Anglo-American Law (Ed. Tanaka) gives "gisei" for "constructive" and Kenkyusha E>J gives "suitei sagi" for "constructive fraud," but Kenkyusha's E>J does confirm that "suitei," "gisei," _and "jun"_ are interchangeably used for "constructive" (see entry under "constructive."
P.S. Dasitkin, I see that you are a licensed attorney in California. Thank you very much for sharing your knowledge and experience with us. I'm a U.S. patent agent, so maybe as time goes on I can return the favor. ---GTP

"Jun" is used in Japanese legal language to refer to something which, while not exactly fitting the definition of the crime, etc. to which the name refers, but which is defined by a specific statute to fulfil the elements. An example would be "Jun-Goukanzai", which refers to statutory rape: sexual relations with a minor under