In a nutshell, Verizon said AT&T’s request to have the ads pulled is without merit. From the court filing (PDF):

AT&T did not file this lawsuit because Verizon’s “There’s A Map For That” advertisements are untrue; AT&T sued because Verizon’s ads are true and the truth hurts… AT&T now is attempting to silence Verizon’s ads that include maps graphically depicting the geographic reach of AT&T’s 3G network as compared to Verizon’s own 3G network because AT&T does not like the truthful picture painted by that comparison.

In the court filing, Verizon outlines the reasons that AT&T’s arguments are without merit. They include:

• Because the ads are truthful, AT&T is attacking them under faulty theories, including a claim that they are misleading. But Verizon says there’s no real evidence – aside from an AT&T commissioned survey – that proves that consumers are misled by the ad.
• There is no emergency that would require the court to issue an immediate restraining order – as AT&T has requested – without giving Verizon the opportunity to conduct its own research and present evidence to prove that consumers are not being misled.
• The harm to Verizon and the public, in general, caused by pulling the ads is greater than any alleged harm being inflicted on AT&T.

Read more about this topic by Sam Diaz at ZDNet