Security expert Bruce Schneier warns against building technologies that could later enable authoritarian surveillance. Imagine a government collecting detailed personal data—like sexuality—for seemingly benign civic planning. Initially trusted, that same database becomes dangerous when a hostile regime takes power, using it to target and persecute individuals.

With existing measures like Cameron's web filtering, ISP "black boxes" tracking online activity, and NHS data sales, the risk is real. Schneier argues it's poor "civic hygiene" to create systems easily repurposed for oppression. While some databases (e.g., car ownership) serve clear public functions with limited abuse potential, others—like national registries of religious beliefs—cross ethical lines.

The core principle: design with future misuse in mind. Just as society rejects tracking race or religion due to historical atrocities, engineers and policymakers must resist creating tools that could facilitate a police state. Civic hygiene isn't distrust of today's government—it's prudent skepticism toward tomorrow's.

Ultimately, the responsibility lies with technologists to build safeguards into systems, ensuring data collection serves the public good without enabling future harm.