@mysteryman,
DADT was part of the military funding bill that Republicans blocked, as stated above.
As far as Obama's stand and why he is allowing DoJ to appeal, I found this:
http://www.huffingtonpost.com/2010/10/14/dadt-repeal-obama-vows-to_n_763610.html#
Quote:
....
Berle urged Senate Majority Leader Harry Reid "to do what it takes in the lame duck session (after the Nov. 2 election) to end 'don't ask, don't tell' legislatively."
Obama agreed.
Speaking at an event sponsored by entertainment networks MTV, BET and CMT, he said, "Congress explicitly passed a law that took away the power of the executive branch to end this policy." He called on the Senate to join the House in passing legislation that would let him end the ban.
"We have, I believe, enough votes in the Senate to go ahead and remove this constraint on me," he said. He added, "Anybody should be able to serve – and they shouldn't have to lie about who they are in order to serve."
The president did not discuss his administration's response to the judge's order.
White House spokesman Robert Gibbs said the president had been "very involved" in discussions about the judge's ruling, including holding meetings with the White House counsel's office to discuss the implications.
"I don't think we're deferring to Congress," Gibbs said. "The president has been active in encouraging and imploring Congress to do the right thing and end a harmful, discriminatory, unjust law."
A person in the government familiar with the case said the White House involvement in the Justice Department's handling of the case figured in the delay in responding to the judge's order.
This person, speaking on condition of anonymity to discuss the administration's internal deliberations, said a couple of White House lawyers did not want to seek a court order that would temporarily suspend the judge's ruling. The source said the process was now back on track.
Defense Secretary Robert Gates has warned of "enormous consequences" for troops if the court order is allowed to stand, saying the decision on whether to repeal the law should be made by Congress and not the courts.
Gates has said he wants more time to prepare for a circumstance in which, for the first time, gay members of the military could declare their sexual orientation without fear of dismissal. .......
So, it appears Congress, back when DADT was passed and signed into law, specifically wrote into the law that the Executive branch couldn't change it.
It also appears, from what I am reading, that Obama specifically wants Congress to do away with the law, rather than the courts.
I can see this being the right way to do it. If Congress does it, it is law. If Congress does it with a fairly balanced seating of Dems and Repubs, it is easier for the masses to digest. (specifically those that might be opposed) If the Courts do it, it is activism, gets appealed and mired in muck all the way to the Supreme Court with further delays, activism and political grandstanding.
And, with the understanding that it is going to change... Gates needs time to prepare.
I'm good with that.