Delaware DUI Laws — 21 Del. C. 4177, IID Election & Penalties

Delaware DUI Laws Explained

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A Delaware DUI conviction triggers two parallel processes: a criminal case under 21 Del. C. §4177, prosecuted in the Court of Common Pleas, and an administrative Delaware DMV revocation that is satisfied by serving the revocation period or by making the IID Election. Delaware made ignition interlock mandatory for every DUI conviction in 2014 — the only path to continued driving in Delaware after a DUI runs through an IID.

The legal threshold

Delaware's per-se DUI thresholds:

  • Adults 21+: 0.08% BAC.
  • Drivers under 21: 0.02% BAC (zero tolerance under 21 Del. C. §4177L).
  • Commercial drivers (CDL): 0.04% BAC.
  • Aggravated DUI: 0.16% BAC or higher triggers escalated penalties.

Delaware also charges DUI on impairment evidence below the 0.08% threshold under 21 Del. C. §4177(a)(1) — the "under the influence" branch that doesn't require a specific BAC. Drugged driving (under the influence of any drug, including legal prescription medications that impair driving) is also covered.

The 15-day IID Election window

After a DUI arrest in Delaware, the officer issues a Notice of Revocation and the driver receives a 15-day temporary permit. The driver has 15 calendar days from the arrest to file the IID Election with the Delaware DMV. Filing the IID Election:

  • Allows the driver to continue driving in a vehicle equipped with an ignition interlock device.
  • Suspends the longer administrative revocation that would otherwise begin on day 16.
  • Does not affect the criminal DUI prosecution, which proceeds independently.

Drivers who do not file the IID Election within 15 days serve the full administrative revocation period before any driving privileges are restored. Most drivers eligible for the IID Election take it.

First-offense penalties (criminal)

A first DUI conviction in Delaware typically produces:

  • Up to 1 year in jail (probation usually replaces jail on a first offense without aggravators).
  • Fine of $500 to $1,500 plus court costs and assessments.
  • 12-month license revocation through the Delaware DMV (concurrent with IID Election if elected).
  • Mandatory completion of a state-approved DUI education program within probation.
  • Mandatory installation of an ignition interlock device (IID) for at least 4 months under 21 Del. C. §4177I (mandatory for any DUI conviction since 2014).
  • SR-22 financial responsibility filing for 3 years — see Delaware car insurance.
  • 1 year of probation, often with substance abuse evaluation.

Aggravated DUI (BAC 0.16%+)

A first DUI with a measured BAC of 0.16% or higher triggers Delaware's aggravated DUI provisions:

  • Higher fine ranges starting at $750.
  • Longer mandatory IID period (up to 9 months for a first offense at this BAC).
  • Longer license revocation.
  • Mandatory inpatient or intensive outpatient substance abuse treatment.

Aggravated DUI penalties also apply when the driver had a passenger under 17, when there was a serious crash, or when the BAC was 0.20% or higher (separate enhancement).

Ignition Interlock Devices

Delaware's IID requirement is mandatory for every DUI conviction since 2014. The device is installed at the driver's expense (typically $70-$150 per month plus a $100-$150 install fee) and prevents the vehicle from starting if breath shows alcohol. The IID also performs random rolling tests during driving; failed tests can extend the IID period. Drivers who comply with the IID program can operate the vehicle for any purpose during the IID period. See Delaware license reinstatement for the IID Election filing process.

Chemical test refusal

Refusing a chemical test in Delaware after arrest triggers an automatic 1-year license revocation through the Delaware DMV, separate from any criminal DUI conviction. The refusal is admissible at the criminal trial. Repeat refusals carry escalating revocation periods up to 3 years. Delaware's implied-consent law gives officers authority to demand a breath, blood, or urine test after a lawful arrest; refusal without legal cause results in the administrative revocation regardless of the criminal case outcome.

Repeat offenses

A second DUI within 5 years brings minimum 60 days in jail, longer revocation, longer IID requirement, and mandatory inpatient treatment. A third DUI is a felony in Delaware: 2 to 5 years in prison and revocation up to 15 years. Delaware uses a 5-year lookback for second offenses and a longer 10-year lookback for habitual offender enhancement. Felony DUI also carries a permanent record that affects employment, housing, and federal background checks.

Aggravating factors

  • BAC at or above 0.16% or 0.20%.
  • An accident with serious injury or death (separate vehicular assault or vehicular homicide charges).
  • A child under 17 in the vehicle.
  • A prior DUI within the 5-year lookback window.
  • Refusing a chemical test.

Official sources

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