Top-flight technology lawyer Francis Currie made a trade: Help New York’s Davis Polk & Wardwell get its Silicon Valley office off the ground, and the firm would one day send him to one of its international offices. That drove him earlier this month to sever a coveted and close 15-year working relationship with technology law patriarch Larry Sonsini.

Sonsini was shocked and surprised, but his firm, Wilson Sonsini Goodrich & Rosati, could not compete with the international presence that Davis Polk was offering.