Your usually covered under the liability insurance of the entity your working for. They are allowed cheaper liability insurance premiums if they have workers that are certified, so you have a license. You can be sued yourself which is why its important to find out the whole story with your employer or just take out som personal liability insurance to cover yourself.
Actually the legal issues in Phlebotomy are:
Most cases that I have found involve the Phlebotomist not following general Phlebotomy procedures.
Some cases:
Most cases were settled through binding arbitration, however some cases went to the state supreme court. It's important to understand taht you can give someone perment damge when preforming phlebotomy and to take care and to take your time is important.
Goddess34