Protecting Paris, Defending Europe

The full cost of France's worst terrorist attack in half a century has yet to be tabulated, much less understood. Yet there are already calls for new laws and measures to prevent a repeat, including at a meeting today of the European Union's interior ministers.

That's inevitable. But Europe's security services already have plenty of power and authority. The clearest lesson from last week's events in Paris is that it is impossible to guarantee the safety of a diverse and open democratic society.