Assembled by one person after a night in Central Lockup, working from Louisiana statutes, two fee agreements, and the paperwork the arrest actually generated.
Two attorneys can quote the same case and mean entirely different things. One hands you a single number that covers everything up to a plea, the other quotes an hourly rate against a deposit and tells you the total depends on how the case moves. Neither approach is a trick, and both are common in impaired driving work, but the difference in what you end up paying can be large, and the difference is usually decided by events that happen months after you sign. A careful reader treats the fee agreement as the document that says which events cost extra.
What a flat fee is actually buying
A flat fee is a fixed price for a defined stage of work, and the definition is the part that matters. In most drunk driving cases the defined stage is everything from being hired through arraignment, discovery review, negotiation with the prosecutor, and resolution by plea or dismissal. That is a real body of work: reading the police report, watching the dash and body camera footage, pulling maintenance and calibration records for the breath instrument, filing pretrial motions, and appearing at whatever status conferences the court sets. What the flat fee usually stops short of is trial, and sometimes it stops short of a contested evidentiary hearing too.
The reason is simple arithmetic on the attorney's side. A trial consumes days that cannot be sold twice, and no one can predict at intake which cases will get there. So the standard structure is a base fee for the pretrial phase and a separate trial fee, quoted up front, that becomes due if the case is set for trial or at some earlier trigger like the day jury selection is scheduled. That trigger is worth finding in the written agreement, because a fee owed when trial is set is different from a fee owed when trial begins.
Where hourly billing changes the picture
Hourly billing puts the risk on you instead of the lawyer. You pay a retainer, which in this context means money held in a client trust account and drawn against as work is done, and you get statements showing time in increments, usually tenths of an hour. The advantage is honesty about short cases: a first offense with clean video that resolves at the second setting will cost less hourly than under a flat quote priced for the average. The disadvantage is that a case that turns into a fight, with suppression motions and a two-day trial, has no ceiling unless the agreement writes one in. Some offices blend the two, charging flat through pretrial and hourly beyond it.
The costs that sit outside either arrangement
Almost every fee agreement separates fees from costs, and costs are billed to you regardless of the structure. Expert witnesses are the big one. A forensic toxicologist who reviews a blood chromatogram, or a former officer who examines whether the standardized field sobriety tests were administered the way the National Highway Traffic Safety Administration's training curriculum prescribes, charges for review, for a written report, and for court time including travel and waiting. That last piece surprises people, since experts commonly bill a half or full day for a hearing that takes forty minutes. Add investigator time, subpoena and records fees, transcript orders, and filing costs, and the separate line can run into real money.
The favorable news is that these are knowable in advance. An attorney who has hired the same toxicologist for years can tell you the going rate for a records review, the rate for testimony, and roughly how often a case like yours needs one. Ask for that estimate in writing, and ask who authorizes the spending, because a good agreement requires your approval before a cost above some threshold is incurred.
Questions to put before you sign
Ask what specific event ends the flat fee and starts the trial fee. Ask whether the license suspension hearing before the state motor vehicle agency is inside the quote or billed separately, since it is a separate proceeding with its own deadline. Ask what happens if you decide to plead after paying the trial fee, and whether any part is refunded. Ask who will actually appear at each setting, an associate or the attorney you met. Ask how appeals, probation violations, and restricted license petitions are priced. Then read the agreement slowly, at home, before you sign it.
The lawyer who answers those questions in plain numbers is telling you something useful about how the office runs. Fee structure is not the whole of a hiring decision, but it is the part you can verify on paper before you commit.