Defense attorneys often challenge law enforcement's use of image tools to copy suspects' computer hard drive files for evidence. There have even been claims that image tools actually alter the computer files during the imaging process.

The National Institute of Standards and Technology (NIST) has set up a testing program that evaluates image and write blocker software to precisely assess how well the tools function.

The goal of the Computer Forensic Tool Testing project is to provide law enforcement agencies with the documentation they need to ensure that recovered digital evidence stands up in court. The project is being funded by the National Institute of Justice.