Delaware's rule on DUI penalties turns on a feature the national template does not capture: BAC limits: 0.08% for adults; 0.04% for commercial drivers; zero-tolerance for drivers under 21. A first offense: First-offense DUI is typically a misdemeanor with fines, possible jail, license revocation, alcohol program, and ignition-interlock eligibility conditions. Felony threshold: A third DUI within a defined period, or DUI with serious injury/death, can be a felony. The controlling authority is Del. Code Ann. tit. 21, § 4177. Lookback: Prior DUI offenses within 10 years (and longer windows for some felony tracks) enhance penalties.. Ignition interlock: Ignition interlock is commonly required for restricted driving privileges after DUI.
Key takeaways
- BAC limits: 0.08% for adults; 0.04% for commercial drivers; zero-tolerance for drivers under 21
- Lookback period: Prior DUI offenses within 10 years (and longer windows for some felony tracks) enhance penalties.
- First-offense range: First-offense DUI is typically a misdemeanor with fines, possible jail, license revocation, alcohol program, and ignition-interlock eligibility conditions.
- Felony threshold: A third DUI within a defined period, or DUI with serious injury/death, can be a felony.
- Ignition interlock: Ignition interlock is commonly required for restricted driving privileges after DUI.
- Primary authority: Del. Code Ann. tit. 21, § 4177.
Worked example under Delaware law
The illustration below uses only rules already stated for Delaware. It is a research hypothetical, not a prediction of what a court will do.
A driver in Delaware is charged with a first impaired-driving offense and wants to know what the statute actually sets.
- Start with the alcohol limits: 0.08% for adults; 0.04% for commercial drivers; zero-tolerance for drivers under 21
- Read the first-offense range: First-offense DUI is typically a misdemeanor with fines, possible jail, license revocation, alcohol program, and ignition-interlock eligibility conditions.
- Ask when the charge becomes a felony: A third DUI within a defined period, or DUI with serious injury/death, can be a felony. Lookback: Prior DUI offenses within 10 years (and longer windows for some felony tracks) enhance penalties.
- Interlock: Ignition interlock is commonly required for restricted driving privileges after DUI.
Delaware DUI under title 21 § 4177 proceeds in the Court of Common Pleas or Superior Court depending on the charge. Parallel DMV actions apply. Defense reviews the stop and Intoxilyzer record.
Blood alcohol limits in Delaware
0.08% for adults; 0.04% for commercial drivers; zero-tolerance for drivers under 21
Lookback window for prior offenses
Prior DUI offenses within 10 years (and longer windows for some felony tracks) enhance penalties.
First-offense penalties
First-offense DUI is typically a misdemeanor with fines, possible jail, license revocation, alcohol program, and ignition-interlock eligibility conditions.
When a Delaware DUI becomes a felony
A third DUI within a defined period, or DUI with serious injury/death, can be a felony.
Ignition interlock and license consequences
Ignition interlock is commonly required for restricted driving privileges after DUI.
How a typical Delaware DUI case unfolds
Delaware DUI under title 21 § 4177 proceeds in the Court of Common Pleas or Superior Court depending on the charge. Parallel DMV actions apply. Defense reviews the stop and Intoxilyzer record.
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Case law: DUI penalties in Delaware
STATE of Delaware, Defendant Below, Appellant, v. Richard MAXWELL, Plaintiff Below, Appellee
…the offenses of Vehicular Homicide in the Second Degree and Driving Under the Influence. Maxwell filed a pre-trial motion to suppress the results of a blood alcohol test taken by the State. Maxwell’s motion was granted by the Superior Court, on the grounds that the *927 police lacked probable cause to take a sample of Maxwell’s blood for testing. The issue presented in this app…
On DUI penalties, STATE of Delaware, Defendant Below, Appellant, v. Richard MAXWELL, Plaintiff Below, Appellee speaks to the Delaware dispute in this passage: "Vehicular Homicide in the Second Degree and Driving Under the Influence. Maxwell filed a pre-trial motion to suppress the results of a blood alcohol test taken by the State." The surrounding opinion shows how the court applied that language to the record.
Roosevelt H. BEASE, Defendant Below, Appellant, v. STATE of Delaware, Plaintiff Below, Appellee
…aised by Bease in this appeal relates to his conviction for Driving Under the Influence of Acohol. Bease contends that the Superior Court erred in denying his motion to suppress the results of an intoxilyzer test. Bease argues that the police officer who stopped him for the Improper Lane Change did not have probable cause to administer the intoxilyzer test, in violation of DehC…
Practitioners open Roosevelt H. BEASE, Defendant Below, Appellant, v. STATE of Delaware, Plaintiff Below, Appellee when Delaware DUI penalties turns on the distinction in this sentence: "Bease in this appeal relates to his conviction for Driving Under the Influence of Acohol. Bease contends that the Superior Court erred in denying his motion to suppress the results of an intoxilyzer test." Do not lift it out of the facts the court was deciding.
Edmund P. LEWIS, Jr., Defendant Below, Appellant, v. STATE of Delaware, Plaintiff Below, Appellee
…of the proper instruction to the jury in a prosecution for driving under the influence of alcohol. We hold that the trial court here erred in its instruction to the jury. In a case where the defendant’s blood alcohol concentration (“BAC”) is over 0.10 percent by weight as shown by chemical analysis of a sample taken within four hours of the alleged offense, 21 Del.C. § 4177(b)…
On DUI penalties, Edmund P. LEWIS, Jr., Defendant Below, Appellant, v. STATE of Delaware, Plaintiff Below, Appellee speaks to the Delaware dispute in this passage: "We hold that the trial court here erred in its instruction to the jury. In a case where the defendant’s blood alcohol concentration (“BAC”) is over 0.10 percent by weight as shown by chemical analysis of a sample taken within four hours of the alleged offense, 21 Del.C." The surrounding opinion shows how the court applied that language to the record.
Kevin L. ZIMMERMAN, Defendant Below, Appellant, v. STATE of Delaware, Plaintiff Below, Appellee
…f sentences imposed on two convictions of the defendant for driving under the influence of alcohol (“DUI”), we consider first the proper standard for admitting evidence of “horizontal gaze nystagmus” (“HGN”) 1 tests in prosecutions for driving under the influence of alcohol or drugs. The HGN test is scientific in nature and the State must establish a proper foundation before ev…
Practitioners open Kevin L. ZIMMERMAN, Defendant Below, Appellant, v. STATE of Delaware, Plaintiff Below, Appellee when Delaware DUI penalties turns on the distinction in this sentence: "DUI”), we consider first the proper standard for admitting evidence of “horizontal gaze nystagmus” (“HGN”) 1 tests in prosecutions for driving under the influence of alcohol or drugs." Do not lift it out of the facts the court was deciding.
Michael D. SHAHAN, in His Capacity as Director of Division of Motor Vehicles, Appellee Below, Appellant, v. Raymond
…appellee, Raymond E. Landing (“Landing”), was arrested for driving under the influence of alcohol in violation of 21 Del.C. § 4177(a). Incident to the arrest, Landing refused to submit to an intoxilyzer test, thus triggering the provisions of 21 Del.C. § 2742, which provides, inter alia, for an administrative hearing which could result in the revocation of the arrestee’s drive…
Michael D. SHAHAN, in His Capacity as Director of Division of Motor Vehicles, Appellee Below, Appellant, v. Raymond is worth reading on Delaware DUI penalties because the court put the point in its own words: "Raymond E. Landing (“Landing”), was arrested for driving under the influence of alcohol in violation of 21 Del.C. § 4177(a). Incident to the arrest, Landing refused to submit to an intoxilyzer test, thus triggering the provisions of 21 Del.C." Use that passage as the starting point, then read the facts that precede it.
STATE of Delaware v. Raymond W. LYNCH
STATE of Delaware v. Raymond W. LYNCH, 1971 Del. Super. LEXIS 158 (1971)
QUILLEN, Judge. The defendant was convicted of driving under the influence by a jury. After initially refusing to take a breath test, the defendant on request was permitted to talk to his attorney and thereafter consented to the test on the advice of his attorney.. A breath test was taken and the results admitted into evidence. It showed a reading of 0.132 percent…
On DUI penalties, STATE of Delaware v. Raymond W. LYNCH speaks to the Delaware dispute in this passage: "QUILLEN, Judge. The defendant was convicted of driving under the influence by a jury. After initially refusing to take a breath test, the defendant on request was permitted to talk to his attorney and thereafter consented to the test on the advice of his attorney.." The surrounding opinion shows how the court applied that language to the record.
James STEWART, Defendant Below, Appellant, v. STATE of Delaware, Plaintiff Below, Appellee
…mes Stewart, was convicted in the Court of Common Pleas for driving under the influence and causing a head-on collision with injuries on February 23, 2003. On this appeal, Stewart does not challenge the Court of Common Pleas conviction. Stewart only challenges the Superior Court’s holding that he must be sentenced as a repeat offender under Title 21, sections 4177(d) and 4177B(…
James STEWART, Defendant Below, Appellant, v. STATE of Delaware, Plaintiff Below, Appellee is worth reading on Delaware DUI penalties because the court put the point in its own words: "Stewart, was convicted in the Court of Common Pleas for driving under the influence and causing a head-on collision with injuries on February 23, 2003. On this appeal, Stewart does not challenge the Court of Common Pleas conviction." Use that passage as the starting point, then read the facts that precede it.
Alfred C. BERTOMEU, Defendant Below, Appellant, v. STATE of Delaware, Plaintiff Below, Appellee
…rto-meu, who was convicted in the Court of Common Pleas for driving under the influence of intoxicating liquor. Appellant sought to exclude from evidence the results of a blood alcohol test performed on him on August 3, 1972. The Court of Common Pleas denied the motion to suppress, and the Superior Court affirmed that decision. We believe the evidence should have been suppresse…
On DUI penalties, Alfred C. BERTOMEU, Defendant Below, Appellant, v. STATE of Delaware, Plaintiff Below, Appellee speaks to the Delaware dispute in this passage: "Court of Common Pleas for driving under the influence of intoxicating liquor. Appellant sought to exclude from evidence the results of a blood alcohol test performed on him on August 3, 1972." The surrounding opinion shows how the court applied that language to the record.
Frequently asked questions
What is the legal BAC limit in Delaware?
0.08% for adults; 0.04% for commercial drivers; zero-tolerance for drivers under 21
Is a first DUI a felony in Delaware?
A third DUI within a defined period, or DUI with serious injury/death, can be a felony.
Will I need an ignition interlock device?
Ignition interlock is commonly required for restricted driving privileges after DUI.
This guide covers Delaware impaired-driving law as of 2026. Sentencing grids, administrative DMV rules, and local diversion programs change — verify the live statute and speak with counsel about your charging document.