[lostcolony]

You said a key word here. "Consultant". I would say you, too, are a consultant, by dint of working for a consulting firm.

A consulting firm, at least, a good one, cares about reputation. There's also a huge level of buy in from the business. You said it, -you're the expert-. That's a fact the business hiring you recognizes, and is why they're paying consulting fees. So yes, you're empowered to say no.

A standalone contractor, however, was not hired for his/her expertise, but to instead be slotted in to an existing project to churn out features, or fix things. The company hiring them has invested far less, sought out far less, stands to both gain and lose far less if things sour, and will have no qualms terminating them if so inclined.

I've seen it firsthand, over and over again. Contractors are second class citizens to employees. But employees are second class citizens to consultants.