This career article comes from CIO magazine, but I think the advice applies to all knowledge/information workers:
"Twelve-hour workdays packed with mile-long to-do lists and meetings on top of meetings. Cell phones and BlackBerrys that are always on, and laptops you take home to squeeze in one more hour of work. With companies [& law firms] firmly focused on growth after several long years of belt-tightening, employees’ workloads are heavier than ever. What can you do to cope with on-the-job scope creep? Stand up and say something before your head explodes.
"To help you effectively broach the subject of your insane workload with your boss, heed the following advice from executive coaches and leadership gurus.
[snip]
"’At the moment of additional assignments, it is critical to not immediately say yes,’ says Kay Cannon, a professional business coach in Lexington, Ky., and president of the International Coach Federation. But you also can’t simply say that you have too much work to take on new projects. ‘Coming in only with problems makes you look like a victim. You want to be perceived as a leader,’ says Barbara Somma, a former longtime director at Johnson & Johnson who’s now a professional business coach in Sarasota, Fla."