Slavery is a system in which people are the property of others.[citation needed] Slaves can be held against their will from the time of their capture, purchase or birth, and deprived of the right to leave, to refuse to work, or to demand compensation. In some societies it was legal for an owner to kill a slave. In others it was a crime to kill a slave(wiki pedia)

http://www.qatarliving.com/node/75337

I does not mean a form of 6th century practice of slavery , but a new model slavery in the form of sponsorship laws