And when products finally become obsolete, Greenpeace wants companies to provide free, convenient tack-back programs in all countries where their products are sold.

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Both are following the usual French political rule: spend the first round securing your base, then tack frantically back towards the centre in the second.

ECONOMIST: France's presidential election

MPs attempting to cut back abortion were hoping to tack their amendments to a bill on assisted reproduction, a field with plenty of controversies of its own.

ECONOMIST: Abortion laws: Hard cases and slippery slopes | The

But in early January, Vivendi changed tack again, dumping 55m previously purchased shares back on to the stockmarket and raising euro3.25 billion of cash.

ECONOMIST: Vivendi Universal

He believes that if the Republican Party wants to win back the presidency, it will have to take the same determinedly centrist tack that he has.

ECONOMIST: Rudy Giuliani's middle way

Undaunted by her reception at the conference, Ms. Swan went back to the other participants in the trial and suggested that they pursue a more professional tack including getting approval for the next phase of the trial from an institutional review board, just as traditional studies do.

WSJ: Citizen Scientists Take On the Health Establishment