Is it against the law to use WIFI sniffing?

Many people use WIFI networks to send emails and surf in public places such as coffee shops or hotels without considering security. Surely anyone trying to steal our data through sniffing would be breaking the law? Of course, this depends on the situation. Recently, a judge approved Innovatio IP Ventures's use of packet sniffing tools to intercept Wi-Fi data from certain hotels, cafes, and other public places. Innovatio IP Ventures believes this is protecting itself. The company claims to accuse a number of hotels and coffee shops that provide free WiFi services of infringing on its patents. So far, courts have accepted the company's arguments, finding that data intercepted over open wireless networks was not plagiarism. However, the opposite was true in another case, in which Google was found to have violated privacy laws in 2011. A few years ago, when Google collected data from home wireless networks to create their Google Street View, Google tried to argue that Wi-Fi radios were available to the public. But so far, courts have not embraced that argument.