Without startup funding, have you thought about:
teaching of some sort? For example, you could potentially earn surprisingly large hourly rate teaching legal English in a university to overseas students. I don't know where you are based, but if you're in London or another large city you might consider looking into that (if self-employed, you could work for a number of institutions).
Have you considered legal publishing as a possiblity? I work in publishing and am self-employed, (in a different field), but there is lots of flexibility and various opportunities, from editorial work on legal texts/dictionaries etc to writing the same. Work tends to be broken down into a series of discrete tasks too, so there is a possibility on working on fewer or more of these in any one title, depending on your availability.
If you have languages, there might be opportunities in specialised translation work too, although that would probably require further qualifications.
Not sure what kind of law you were in, but I would imagine there are lots of transferable skills such as giving presentations/writing clearly etc, which you might be able to turn into some sort of business (eg a consultancy teaching people how to write a good CV or how to present at meetings, or whatever - a variety of courses perhaps).