First of all, the Federal minimum-wage law applies only to businesses engaged in interstate commerce, so all restaurants do not have to comply (although many states have similar laws, some with higher minimums, in fact). In those cases where the Federal law does apply (national chains, for example), the rule is that the sum of wages plus tips must equal the minimum wage. If tips fall short, the employer must make up the difference. Requiring employers to pay minimum wages on top of tips would presumably overcompensate these employees, but that's a value judgment, of course.

Bruce