Dike, Bronstein, Roberts & Cushman LLP (DBRC) (defendant) was a law firm specializing in patent, trademark, and copyright law. DBRC was organized under a partnership agreement. One section of the partnership agreement provided that when a partner left DBRC, he or she had to make payments to DBRC for any work the partner continued to do for current or former DBRC clients. Ronald Eisenstein and David Resnick (plaintiffs) were partners at DBRC. In 1999, Eisenstein and Resnick left DBRC to join a different firm, Peabody & Brown (Peabody). At Peabody, Eisenstein and Resnick worked for present and former DBRC clients. In 2001, Eisenstein and Resnick filed a complaint against DBRC and others seeking payments allegedly due to them under the DBRC partnership agreement, including for their share of profits and a return of capital contributions. DBRC filed a counterclaim for breach of contract and fiduciary duty. Eisenstein and Resnick moved for summary judgment, arguing that the provisions of the partnership agreement requiring payment to DBRC for work done for current or former DBRC clients after a partner left the firm were void and unenforceable under Rule 5.6 of the Massachusetts Rules of Professional Conduct. The trial court granted summary judgment in favor of Eisenstein and Resnick. DBRC appealed.