Many start-ups use their Social Network contacts to find additional workers. Why not? Someone's friend of a friend is probably that chef, programmer or administrative assistant you need, and they're looking for work. (In fact, Inc. has a great guide to Using Social Media as a Recruiting Tool.)

But beware how you use that Social Network data you find. It could lead to discriminatory hiring practices. Most start-ups don't have an HR department to tell them that different restrictions take effect when you have 4 employees, 15 employees and as you grow past 20 and 50. The Federal Equal Employment Laws prohibit employment discrimination against qualified individuals with disabilities, and prohibit bias based on race, color, religion, sex, or national origin, age, as well as other considerations. State and Local laws may impose even stricter rules depending on where your business operates.

This data (a candidates race, national origin, pregnancy status, etc.) is considered 'protected information' and you can't ask it in an interview. If it is revealed to you, it is often best to keep it to yourself and not pass it along to other hiring managers.

But what happens when the candidate reveals protected information via their social profiles? A Facebook basic profile almost matches the list of things you can't ask in an interview – race, religion, sexual orientation, relationship status - are all part of the standard questions many people fill in on their pages.

'Social Media is an issue in HR and Employment and Compliance law – the protected information on people's profiles is free, easy and voluntary. It's not as if the employer is asking 'are you pregnant' in an interview,' said lawyer Nancy Schess, a partner at Klein Zelman Rothermel, a labor and employment boutique firm that represents management. 'The questions to ask are is a)it legal and b) is it a best practice to go and look for this information in the context of your hiring practice.'

Schess continues 'Yes, If you go on a search engine and you can find it, you are allowed to look at it. But once you have the information, legally, what can you do with it?'

Take the case of a start-up owner who needs new assistant. He asks his network or his HR person to get candidates. He interviews an outstanding woman candidate and practically offers her the position during the interview. Then he finds out via her Facebook status after the interview that she's 3 months pregnant. The owner knows that 6 months from now when she's out giving birth, it will be the busy season, when he can't afford to be without help. Legally he can't act on this information.

I asked Schess, 'How do you 'un-know' this in your decision making process?' She replied 'You can state you didn't take it into account, but if you are sued for discrimination you have to prove that it wasn't part of the decision making process. Now you're in a risk area with a large liability.'

Is this kind of worrying really relevant to hard driving, fast-decision-making startups? 'It's my opinion in working with students and startups that they typically don't care about this kind of information. They want qualified candidates,' says Dan Cohen, a Lecturer in Human Resource Studies at my alma mater, Cornell University's School of Industrial and Labor Relations. Cohen was a 15-year entrepreneur who sold his own business and earned a PhD. in Management. He's also the Entrepreneur-in-Residence at Cornell's Student Agency's eLab Incubator. 'When start-ups need specialized talent they want the people that can do the job. The need for that talent is often blind to other personal characteristics.'

Schess cautions 'If you're going to use Social Media, and it is an appropriate approach, there's a way to do it that protects you. Separate the information gathering, so the person who does the online search isn't part of the hiring chain. Perhaps a screening agency, or a different employee. You have that person look at a candidate's online profile for legitimate business issues, then ask them to brief you about their educational background and business experience. Make sure they don't tell you about their protected information.'

Do you recruit candidates using Social Media? What's been your experience? 

Note: You should consult your own attorney before relying on these procedures - employment law varies by state and locality.