One of my first jobs was at a company that sold and serviced surveillance equipment to school districts. It's a slippery slope where you can first focus on the good aspects -- murder cases solved -- but eventually encounter information that you have to make an ethical judgement on wether you are willing to play a role in implementing such technology. For instance, testing began on systems that could capture both audio and video and I became uncomfortable because kids say stupid things that can be taken out of context. I make no claims that audio surveillance was installed, but the casual nature of doing R&D on such systems without considering the implications became too uncomfortable for me to take part of.