I told my boss I had an idea for a program that could improve efficiency across much of the business, and he let me build it on company time. In the long term, he wanted to be able to sell it to other companies. However, the program never got implemented due to personnel mismanagement, and I'd rather be able to post it on my github under a free licence so I can use it as a resume item, and at least someone would have the chance to actually use it. It's all still in my head, and I could write it again if I wanted. If I do, is it illegal to publish it? What if I write it in a different language? Do I need to change the variable names? I did plenty of research and planning on company time to build it, and it's not like I can research it again, it's all still in my head.
Legally it is quite clear. Taking a description of a closed source program and writing a new one is ok in most cases (unless that description is API docs - see Cisco vs Arista). Taking a look at closed source software and then implementing your own version is poison as far as OSS goes. OP implemented the first version, so that's already a problem. They may get away is they describe what the program does to someone else and let them implement it, but OP would not be able to touch the source code
I agree. Particularly because it's less about the truth and more about what can be proven in court. But even more, they don't want to pay a lawyer a bunch of money to defend this even if you could prove it beyond a shadow of a doubt. You can tell by the way they didn't want to pay a lawyer to answer this question.
Having seen original source code hasn't been an issue in previous cases where the reimplementation was done in another language with the changes one would expect coding up something a second time, I believe