From illegal to socially accepted:
- illegal and immoral
- still illegal, but more and more people start doing it
- start of decriminalization, grey area
- fully legal and accepted by society
- the obvious right thing to do
As exemplified by gay rights or marijuana legalization, at various stages of this process.
Broad government surveillance stifles this process by preventing the change from step 1 to 2 and thus hinders social progress.
Freely paraphrased after Bruce Schneier at Defcon 23. Wisdom is due to Bruce, mistakes are mine.