Scraping Law Firms Legality - I will not promote

Hi all, My cofounder and I have been developing a tool that scrapes law firm directories and then tracks any movement to and from the directory in order to follow the movements of lawyers. The idea is to then sell this data (lawyers name, contact number on directory, email address, and position) to a specific industry that would find this kind of data valuable. Is this legal to do? Are there any parameters here, and is there anything that we need to be careful of?