An attorney who assists in or shares the responsibility of representing a client.
– Merriam-Webster dictionary
One of two or more lawyers working together on a legal case.
– Cambridge dictionary
The co-counsel model of legal representation is often used by large, sophisticated corporate defendants when their corporate legal department decides they need specific skills and talents from lawyers at different law firms. For example, a corporation will often have one law firm handle discovery, while another law firm is local counsel and a combination of law firms share the responsibility for different aspects of liability or damages and different fact and expert witnesses to give them what they believe is the greatest advantage to win.