Lind ruled on the first day of a scheduled four-day hearing at Fort Meade, near Baltimore.
The hearing is partly to determine whether Manning's motivation matters. Prosecutors want the judge to bar the defense from producing evidence at trial regarding his motive for allegedly leaking hundreds of thousands of secret war logs and diplomatic cables. They say motive is irrelevant to whether he leaked intelligence, knowing it would be seen by al-Qaida
Manning allegedly told an online confidant-turned-informant that he leaked the material because "I want people to see the truth" and "information should be free."
Defense attorney David Coombs said Tuesday that barring such evidence would cripple the defense's ability to argue that Manning leaked only information that he believed couldn't hurt the United States or help a foreign nation.
Manning has offered to take responsibility for the leaks in a pending plea offer but he still could face trial on charges such as aiding the enemy.
The Crescent, Okla., native is accused of leaking classified Iraq and Afghanistan war logs and more than 250,000 diplomatic cables while working as an intelligence analyst in Baghdad in 2009 and 2010. He is also charged with leaking 2007 video of a U.S. helicopter crew gunning down 11 men, including a Reuters news photographer and his driver. The Pentagon concluded the troops acted appropriately, having mistaken the camera equipment for weapons.
Manning supporters consider him a whistleblower whose actions exposed war crimes and helped trigger the pro-democracy Arab Spring uprisings in late 2010.
Associated Press writer Ben Nuckols at Fort Meade contributed to this story.