Race Riots in Paris - The Guardian has the answer.
The latest outbreak of unrest has focused attention on France's sink estates, where petty crime and drug-dealing are rife and unemployment can reach or surpass 50%. Built to house immigrant workers after the second world war and the families who later came to join them, many of these citÚs are today sink estates with little possibility of escape.
The country's immigration and integration policy is based on one of the founding principles of the republic that all its citizens are equal. Few politicians will yet admit, however, that radical and anti-republican measures such as positive discrimination may now be unavoidable.