Littler Mendelson, a national firm whose Web site proclaims it as a source for “Employment and Labor Law Solutions Worldwide,” is having its mettle tested in a suit by a former employee of its Newark, N.J., office.

The threshold question in Preston v. Littler Mendelson, L-2370-9, is whether the law firm can compel arbitration based on agreements it drafted that it says bind all employees suing the firm.