Law firms are marking the 10th anniversary of Pro Bono Week with events on topics ranging from voting rights to immigration that encourage attorneys to volunteer their time professionally.

Pro bono at big firms, especially, has proliferated over the past two decades with many running full departments with directors and staff to manage the caseload, Anthony Perez Cassino, pro bono counsel at Milbank, Tweed, Hadley & McCloy, has said.

Pro Bono Week “is like our Olympics” because we have a series of events spread out over several days, Allegra Nethery, pro bono and philanthropy partner at Seyfarth Shaw, said....