In a rather surprising ruling, the Yokohama District Court in Japan has acquitted a man of secretly operating software on his website that used his site visitors’ spare computing power to mine crypto without them knowing.

The practice is known in the industry as “cryptojacking”. Japanese media reported (Mar 27) that the 31-year-old web designer had used Coinhive, a JavaScript miner for the Monero blockchain that can be embedded in a website.

Prosecutors had asked for the man to be fined JPY 100,000 ($903) for running the program without the knowledge and consent of site visitors. They did not know their computers had been used, and that their electricity consumption had increased as a result of mining.

The defense, however, called for his acquittal, arguing the program was not meant to damage visitors’ computers or infringe their personal privacy.

In clearing the man of the case, Presiding Judge Toshihiro Homma agreed with the defense, saying the man’s action “does not constitute a crime as we cannot say embedding the program was socially unacceptable”. It would, therefore, be “excessive” to punish him as the program’s impact on site visitors was also deemed to be minor.

Yokohama’s District Public Prosecutors Office said it will study the ruling of the case.

Even if this web designer should want to continue using Coinhive, however, it is already not possible – Coinhive announced at the end of February that it was shutting down. All its in-browser mining scripts have stopped operating since March 8, and users have until April 30 to withdraw any Monero they have left.

Coinhive cited three main reasons for its closure – the sharp decline in the value of Monero, the increased technical difficulty over time to mine it, and the overall risen cost in mining.

Around the same time as the Japanese case, Ukrainian media reported (Mar 26) that Ukraine’s cyber police had captured a 32-year-old man from the Bukovina region, for cryptojacking on various educational websites he created. The police said it was illegal to take advantage of site visitors’ CPU and GPU power to mine crypto.