HR are on your side when your interest and theirs are congruent and when they recognize that. You'd think that it would be in the company's best interest to avert lawsuits, but that doesn't mean that they act accordingly. My former employer paid ten millions in settlements in the last two years, several lawsuits are being litigated now, and even more suits are coming down the pike.

HR is on your side, when you are an useful pawn to dethrone someone else the company or some political group wants to get rid of.

Of course, gratitude is not a common virtue on the corporate world, and you're now marked for execution in a near future convenient time.