Iowa has many requirements for someone convicted of an OWI. These requirements are handed down by both the criminal court, and the Iowa Department of Transportation (IDOT).
The IDOT will require any driver that failed a breath test or refused a breath test (whether 1st or any subsequent failure) to take an approved drinking drivers’ course prior to becoming eligible to obtain their license again.
The IDOT accepts both the 12-hour course, and the 48-hour course.
So, apples-to-apples, the 12-hour course should be the obvious choice.
Then why does the 48-hour course exist?
The 48-hour course can be approved by the criminal court to satisfy the State’s requirement for a minimum of 48 hours in jail. This can be required (and in Johnson County is nearly always is) even when a deferred judgment is granted.
Therefore, it is wise to take the 48-hour course only when the criminal court requires or authorizes it. This will allow the driver/defendant to “kill two birds with one stone.”