James Holmes' Lawyers -- Our Client Is INSANE

Lawyers for James Holmes just stated in open court -- they believe their client suffers from a mental illness ... and they need more time to figure out what's wrong with him before entering a plea.

Holmes' attorneys made the announcement during a hearing today, in which several news outlets had assembled to argue that the judge in the case should unseal court documents that could reveal important details about the July shooting in Aurora, CO.

Both the prosecution and the defense wish to keep the documents under wraps while the case is pending.

While everyone was in court, Holmes' attorney also appealed to the judge on an unrelated note -- demanding prosecutors and investigators turn over ALL documents related to the case ... in order to help the defense team determine just how crazy their client is.

The lawyer said, "We cannot begin to assess the nature and the depth of Mr. Holmes' mental illness until we receive full disclosure of all the documents."