Heller Ehrman is a significant force on the West Coast and one of the largest San Francisco firms. Last year its revenue hit £261m ($475m), while average profit per equity partner stood at £486,000 ($885,000).

The firm is rare among US firms in the Global 100 in that it has no European presence.

However, in February 2006, Heller hired Ted Hennebury from the Irish Competition Authority as its first European development partner.

Hennebury frequently visits London and other European destinations to scout out potential offices, with both Milan and London current priorities. However, no office opening had been confirmed at time of going to press.

Heller's IP and IT specialist practice areas are well served by offices in Singapore, Beijing and Hong Kong, but the offices arguably lack the same level of experience with Japanese clients as San Francisco rival Morrison & Foerster.

The firm's IP practice has had a bumpy ride on the East Coast recently. In March, Heller lost four life sciences and IP partners to New York-based Proskauer Rose.

Colin Sandercock, formerly co-chair of Heller's patents & trademark group, John Isacson, Paul Booth and David Laub left Heller's office in Washington DC to join Proskauer's office in the capital.

• The Top 100: 26-50