Late Thursday night, two of the groups that invited Coulter issued an ultimatum threatening legal action if the event didn't go on as scheduled. On Friday afternoon, Berkeley responded with its own letter.
The attorney filing the lawsuit calls Berkeley's letter a non-response.
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Attorney Harmeet Dhillon said the lawsuit her firm is filing against UC Berkeley is not about money or Ann Coulter. "This is about Berkeley's persistent refusal to honor the constitution when it comes to conservative speech on campus," she said.
Dhillon said this is the third instance of Berkeley canceling conservative speakers. "The same hassles, unconstitutional requirements and bait and switch that Berkeley did with the Milo Yiannopoulos speech," she said.
In a letter, the university's legal counsel says UC Berkeley has dedicated more resources to facilitating Berkeley College Republicans' activities than to any other student group in memory.
After initially canceling Coulter's April 27 visit, the university proposed a May 2 alternative -- a date Coulter says she is not available.
"Where Berkeley permits limited use of its space for certain viewpoints, it is required under the constitution to provide equal access to other groups," Dhillon said.
While Berkeley College Republicans and Young America's Foundation support legal action, a third group that initially invited Coulter, Bridge USA, does not.
"To take this to court when they're trying, at least make some efforts, is not the right solution," Bridge USA President Pranav Jandhyala said.
In its letter, the university says its actions have been wholly consistent with its obligations under the constitution to protect free speech rights and the safety and security of the university community.
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Click here to view UC Berkeley's full letter.
Click here to read the full letter from Dhillon to UC Berkeley.