The controversy that has surrounded Brenner's results illustrates how difficult it is to draw firm conclusions about the role of any one factor, such as unemployment, on a state as loosely defined as 'health'.

And the controversy that has evolved over the group's role also illustrates the competition and sometimes outright hostility between campaigns and political action committees as they vie for contributions.

Perhaps more than any event in recent years, that controversy illustrates the ambivalence of cultural policies in Mexico.

The controversy not only illustrates the volatile nature of land-use questions in Manhattan, but also has exposed some rifts between environmental-protection groups.

The controversy illustrates that playgrounds have become more than child's play.

"This latest controversy clearly illustrates how the practice of pay-to-play drastically increases the cost of government while at the same time destroying the people's faith in the democratic process."

The controversy over an African church that allows clergy to have more than one wife illustrates the challenges facing the council as it attempts to keep the global ecumenical movement alive.

The controversy surrounding the Rampart Dam project illustrated the growing shift in the environmental movement during the 1960s.

Some recent controversies around scientific publications illustrate the potential benefits of open science.