Where is this from ? May have been taken from where I got it from

Today I made an appearance downtown
I am an expert witness, because I say I am
And I said, gentleman, and I use that word loosely
I will testify for you
I'm a gun for hire, I'm a saint, I'm a liar
Because there are no facts, there is no truth
Just a data to be manipulated
I can get any result you like
What's it worth to ya?
Because there is no wrong, there is no right
And I sleep very well at night
No shame, no solution
No remorse, no retribution
Just people selling T-shirts
Just opportunity to participate in the pathetic little circus
And winning, winning, winning