First, let's understand what an ALR hearing is. In most DWI cases, when you are arrested, a cop offers you a breath test. If you turn down the breath test, or "fail" the breath test, the cop seizes your driver's license and give you a notice of DL suspension.
The notice tells you (in incredibly fine print) that you have to decide within 15 days whether or not you wish to request and ALR hearing -- a hearing to decide if your DL will be suspended. If you do nothing, the Department gof Public Safety gets to automatically suspend your license 40 days after the day of your arrest.
If you request an ALR hearing, then whether or not your DL is suspended gets decided at a hearing conducted by the State Office of Administrative hearings. At the ALR hearing, DPS has to prove two things: (1) that there was probable cause to arrest you for DWI and (2) that you either took a breath test and blew over the legal limit or that you refused to take a breath test. If both of the questions get answered "yes", then DPS gets to suspend your license. If either gets answered "no", then you get to keep your DL. There are some really good reasons for requesting an ALR hearing. First, there is always a chance that you will get to keep your DL.
Maybe you truly do have a probable cause issue. Maybe the DPS will screw up its paperwork or a witness won't show for the hearing. Second, you get to subpoena into the hearing the arresting cop and ask him questions. This gives you a sneak preview of what the officer's testimony might be at a trial. Third, since a record is made of all testimony at the hearing, you get to "freeze" the testimony of the cop so he can't change it later. In addition, if you have a commercial driver's license, then an ALR hearing is practically mandatory, since you cannot get an occupational license to drive a commercial vehicle if your DL is suspended. Finally, if nothing else, requesting an ALR hearing delays any DL suspension, since the DPS cannot suspend your DL while the ALR proceeding is pending.
This delay can be useful to people who driverfor a living, for instance, and who need to time to make arrangements at work or to look for another job. In short, even if your license eventually gets suspended, the ALR hearing can still be an extremely handy tool for preparing for your DWI case -- a tool that , unfortunately, most people with DWIs never use.