Nevertheless, several recent US presidents (of both parties) have issued executive orders requiring federal agencies to use environmentally preferable products and services whenever possible, as has the European Commission.

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Obama issued three executive orders Thursday designed to show a clean break from the Bush administration on the war on terror.

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It revoked all or part of more than a dozen executive orders issued between 1939 and 1991.

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The nearby table shows the number of executive orders issued per year by every U.S. president since 1900.

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During the debate Thursday, Clinton, Edwards and Obama generally agreed they would seek an end to the war in Iraq, scrutinize executive orders issued by President Bush and reform the health-care system.

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On May 6, 1995, the President issued Executive Order 12959 imposing more comprehensive sanctions to further respond to this threat, and on August 19, 1997, the President issued Executive Order 13059 consolidating and clarifying the previous orders.

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While executive orders seem irresistible to presidents because they can be issued quickly, they can be revoked quickly, too.

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Among the more famous (or infamous) executive orders in U.S. history, FDR issued one that forcibly transferred Japanese-Americans and German-Americans to internment camps during World War II.

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President Obama revoked executive orders 13258 (2002) and 13422 (2007), both of which were issued by George W. Bush and amended executive order 12866 (1993) which had been issued by Bill Clinton.

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