"I don't see how an American will be able to represent this senseless coward," one person wrote on a local site.
Another questioned how a retired military officer could take on such a case. He wrote, "Mr. Galligan, you are selling your soul to make a buck."
Galligan retired as a colonel from the Army in June 2001 and is a former military judge on Fort Hood.
Galligan left Belton after 3 p.m. Monday for Brooke Medical Center in San Antonio to meet with his client. He said Hasan's brother called him earlier in the day and hired him.
"It's cases like this that best demonstrate how well our legal system is prepared to react and defend a criminal defendant," Galligan said. "People need to let the system operate the way it is set up to operate. He (Hasan) is protected right now by a presumptive cloak of innocence."
No charges had been filed against Hasan before Galligan was hired, although Galligan said it was his understanding that Hasan already had been advised of his rights.
"No interrogations should be conducted without counsel present or permission of counsel," Galligan said.
It is unclear if Hasan was questioned before Galligan was hired.
