The problem is that this is not a “legal” investigation by Mueller, it is a political one. Thus, it matters not whether they got the data illegally. Yes, it can’t be used in a court of law,but the media and Dems can use it (if there is negative information) to sway public opinion against President Trump.
I don’t agree documents were obtained under color of law and if in violation of law- 4th smendment it is a crime 18 usc 242 also right to privacy