Disk Arbitrator is Mac OS X forensic utility designed to help the user ensure correct forensic procedures are followed during imaging of a disk device.
It is important to note that Disk Arbitrator is not a software write blocker---it does not change the state of currently attached devices nor does it affect newly attached devices to force a device to be read-only. The user still must be careful to not accidentally write to a disk with a command such as "dd". Owing to this fact, a hardware or software write-blocker may still be desirable for the most sound procedure. Disk Arbitrator compliments a write-blocker with additional useful features and eliminates the typical forensic recommendation to "disable disk arbitration."