Can someone explain that to me? Is it against the law to find all publicly available information about someone or to follow them around?

The big criminal act that I can see here is that "Ergo" (the company that Uber hired) wasn't licensed in NY. Seems like that would be on Ergo, not Uber.

Remember, there was previously an incident where an Uber exec bragged at a party about using investigators to destroy journalists who might investigate them. [0]

[0] http://www.dailytech.com/Uber+Exec+Threatens+to+Spend+Millio...

If investigators don't have any power to do anything that a normal public person can do, like finding public information or digging through someone's trash...then I don't see why anyone should be barred from employing that. However, I know that in many states you must be licensed to advertise yourself as a Private Investigator.

I don't know why that would be the case though unless PIs have special authority to do things that normal people can't do. I mean, I do know why - it's political for one thing since you can't even be a PI in some states without having police or military experience.

Looking around, I don't see any special privileges that a PI has that a normal person does not. They cannot trespass on private property, they cannot wiretap a phone or gain access to private records. The only special privilege that they enjoy is that they generally won't be subject to harassment or stalking laws if they follow someone around in public.

If Uber/Ergo had limited itself to not interviewing the plaintiff's family, friends, and acquaintances, they'd probably have been fine; but going around to everyone you know and asking a lot of dark questions is pretty clearly going to intimidate a plaintiff and chill other potential plaintiffs, and that's obviously the point--especially when interviewing is unlikely to surface anything not already found through records searches and the discovery process.