"I've always been particularly confused by the contract clauses which specify that all work of the employee during their time at the company is property of the company itself. Does this mean that if I develop some completely unrelated software in my spare time while working as a programmer at a large company, that the software I created at home also belongs to my employer? "
In most states, the answer is "yes, it probably does".
It varies from state to state, of course, and the definition of "completely unrelated". In the nicer states, it's about what is related to your employers business, or the demonstrable/anticipated research and development of your employer. Most engineers get this very wrong, or have no idea about all the things their company does.
The only common country i'm aware of in which the answer is definitely "no, it belongs to you", is switzerland.
As for legal battles, plenty. Most of the time, the company wins.
I'd say 70-30.
Usually because most companies are willing to come to arrangements to avoid litigation, so when they don't, it's often something egregious (one way or the other, be it company trying to claim something they shouldn't, or employee trying to sell something employer should definitely own).
Switzerland basically says what you do in your own time is yours.
California does not, and does not say what most engineers think it does.
It says companies can own inventions that:
(1) Relate at the time of conception or reduction to practice of
the invention to the employer's business, or actual or demonstrably
anticipated research or development of the employer; or
(2) Result from any work performed by the employee for the
employer.
#1 is read fairly broadly.
Most think it just says #2.
In most states, the answer is "yes, it probably does". It varies from state to state, of course, and the definition of "completely unrelated". In the nicer states, it's about what is related to your employers business, or the demonstrable/anticipated research and development of your employer. Most engineers get this very wrong, or have no idea about all the things their company does.
The only common country i'm aware of in which the answer is definitely "no, it belongs to you", is switzerland.
As for legal battles, plenty. Most of the time, the company wins. I'd say 70-30.
Usually because most companies are willing to come to arrangements to avoid litigation, so when they don't, it's often something egregious (one way or the other, be it company trying to claim something they shouldn't, or employee trying to sell something employer should definitely own).