Since I just read about this in a course, the main reference (at least for Canada/UK/Commonwealth) is the Salomon case from 1895:
https://en.wikipedia.org/wiki/Salomon_v_A_Salomon_%26_Co_LtdSo, not new.
I think people overreact to hearing that corporations are (legal) "persons" when in fact they are not anything like natural persons (no body, no constitutional rights). As I understand it, directors and officers are the ones held personally liable in criminal matters, but corporations can still be liable for negligence and breach of contract etc. IANAL.
Sounds like it is different in the US. Does citizens united somehow make corporations more like people?