A new study by the Palm Center concludes that President Barack Obama has the power to stop discharges of gay military personnel by executive order and without the approval of Congress, should he so choose. The Center has released a "Roadmap of Political, Legal, Regulatory, and
Organizational Steps to Equal Treatment". From the Palm Center's press release:

to promotion, retirement, or separation applicable to any member of the
armed forces who the President determines is essential to the national
security of the United States” during a “period of national
emergency.” The statute specifically defines a “national emergency” as
a time when “members of a reserve component are serving involuntarily
on active duty.”
The second and third bases of presidential authority are contained
within the “don't ask, don't tell” legislation itself. The law grants
to the Defense Department authority to determine the process by which
discharges will be carried out, saying they will proceed “under
regulations prescribed by the Secretary of Defense… in accordance with
procedures set forth in such regulation." Finally, the law calls for
the discharge of service members “if” a finding of homosexuality is
made, but it does not require that such a finding ever be made.
According to the study, these provisions mean that the Pentagon, not
Congress, has the “authority to devise and implement the procedures
under which those findings may be made.”
Read the Palm Center's blueprint here (PDF).
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