Ask HN: As a Big Data engineer, how do I avoid helping governments spy on us?

My career is based on data science, specifically building tools to gather, store, and make sense of large amounts of data. With the recent leaks regarding the NSA over the past couple days, I'm having a bit of an existential crisis so to speak. In fact I can actually envision how systems like PRISM could work and how to build them.

I love my work. It's fascinating and I believe that such powerful systems can do a lot of good. I'm specifically trying to get into bio- and cheminformatics to try and develop technologies that save lives and improve quality of life, but there is a lot of overlap between the technology I develop for that purpose and what Silicon Valley uses to collect innocent citizen data and pass it off to the NSA.

My question is, how do I go about ensuring that my work is only used for the benefit of mankind? Is that possible within my career? Dystopian literature has always fascinated me in a sort of macabre sense, but I absolutely loath the idea of contributing to the technology that oppressive governments would use to spy on their citizens.

Can HN give me some advice?