Should spyware be legal or illegal?

Answer 1

To the degree that spyware extracts information without the clear consent of the individual whose information is being extracted, it should be illegal. It is invasion of privacy and theft of information and services. Most spyware is installed without the knowledge of the user and is correctly classified as malware. Note that some companies install software that can be used to monitor employees and their use of the company computer resources. Such software could be considered "spyware" but in this case there is a significant distinction: the company has required the user to sign an "acceptable use" agreement and posted a disclaimer informing the employee that they will be subject to monitoring - thus the employee has given consent for the information to be collected.

Another reason why malware like spyware should be illegal is that it consumes system CPU cycles and bandwidth, thus stealing performance from the unwitting user.