Can my boss set unrealistic work goals?

Can my boss set unrealistic work goals?:
Dear Evil HR Lady,
I work in a production area where the goals are intentionally set too high. (One supervisor once said, “They’re going to go up on the goal because too many people are meeting it.”) Employees who are deemed troublesome (or perhaps too expensive) are placed on Performance Improvement Plans (PIPs) and ushered out the door a few months later.
My own production goal is going up to 150 percent of the current goal, without any known data that would justify the increase. No one else doing the same work is reaching nearly that high a number.
Two questions: 1) Is this kind of environment legal? 2) How does an employee best defend against being unfairly placed on a PIP?
To answer the question, click here: Can my boss set unrealistic work goals?

DIGITAL JUICE