Is it Ethical for Employers to use Social Media in Hiring and Employment Decisions?

Yes, it is as they are using different strategies to know their applicants.

Yes, it's ethical for me as a HR Recruiter. Specially the situation we're in now. We still don't have a vaccine for COVID-19.

is not a violation of rights.  If you didn't want anyone to see something, you shouldn't have put it there.

Absolutely ethical.  If you don't want your opinions shared with prospective employers, don't post them.

Nope.  YOU put it out there in public...so the public can see it whenever they want.

(drum roll...rimshot)

That depends on what you mean by "use social media".   You gave absolutely zero specifics or details.

It's perfectly ethical to Google someone and see what they are posting publicly for the entire world to see.

IMO it's not ethical to require applicants or employees to give their social media passwords or access to their private pages to employers.

Details are important here and you gave NONE. 

Is there a document stating the “Ethical Rights of Employees?”  Employers must ensure that their employees are suitable. If social media activity indicates someone is violent or hostile, don’t hire them.