The perjury charges present a complicated challenge for the government, Mr. Brown, the former prosecutor, said.

But Democrats, who provided most of the votes for the income tax, face a more complicated challenge.

In the end, doing the right thing in college sports is not really a complicated intellectual challenge.

Still, none of them have anything like the sophisticated management strategies used by American business, medicine or the military for addressing complicated challenges.

But appealing to those loyalties, while still wooing the Independents who decide elections, is a complicated challenge these days.

We need to address broader and more complicated challenges.

Yet on both sides of this divide, there are complicated challenges underground.

But this was an unusually easy military problem and is not a useful guide for the more complicated challenges ahead.

From his own experience working with farmers, he knew that stunning technological advances often brought new and even more complicated challenges.

Today's patient presented us with a rather complicated challenge.