And yet loads of people employed by companies work on open source software, write blogs, work on their own stuff, etc and companies don't seem to get involved. So what's the situation here? Is it something like companies legally may be able to assert ownership over work down by employees of their own volition on their own time with their own equipment, but mostly choose not to bother with it?
Assume I have an "ordinary" contract in the USA. Would I need to worry about this if I wanted to write stuff on a blog, assuming it isn't directly related to work I do?
(I understand that if it really matters I should talk to a lawyer, and will not interpret any responses as legal advice, etc. I'm just curious if other professional employers worry about this or just quietly do their own thing)