Blockburger Double-Jeopardy Tester

Run the Blockburger Test

Enter the statutory elements of each offense, one per line, then run the test. The tool sorts the elements into what is unique to each offense and what they share, and reports whether the two are the “same offense” under Blockburger. It runs entirely in your browser — nothing you type leaves the page.

The Same-Elements Test

The Blockburger test — also called the same-elements test — is the starting point whenever one act or transaction seems to violate two criminal statutes. The rule is compact: two provisions describe the “same offense” unless each requires proof of a fact that the other does not. Blockburger v. United States, 284 U.S. 299, 304 (1932).

The comparison is made on the statutory elements, not on the evidence a prosecutor actually intends to use. If the two offenses, read side by side, each contain at least one element missing from the other, they are separate offenses, and the Double Jeopardy Clause does not bar trying or punishing both. If every element of one offense is also an element of the other, the smaller offense is swallowed — the two are the same, and only one may be pursued.

That is exactly what the tool above does. It sorts the elements you enter into “only in Offense 1,” “common to both,” and “only in Offense 2,” then reports whether each side has something unique. A quick worked example: burglary of a habitation with intent to commit theft and burglary of a habitation with intent to commit assault differ only in the intended felony, so a court still asks whether the Legislature meant them as one offense or two. Text matching is only the first move; the legal characterization of an element is the harder question.

One point worth flagging: the same-elements rule is decisional law. The Fifth Amendment forbids putting a person twice in jeopardy for the “same offense,” but the Constitution never says when two crimes are the same. The Supreme Court supplied that definition in Blockburger, and courts have applied it ever since. The controlling text is short; the test that gives it meaning comes from the case law.

Same Offense Is Not the Same Conduct

A common misunderstanding is that double jeopardy blocks a second charge whenever the government would re-prove the same conduct. For a brief period that was the law: Grady v. Corbin, 495 U.S. 508 (1990), added a same-conduct test on top of Blockburger. The Supreme Court then reversed course.

In United States v. Dixon, 509 U.S. 688 (1993), the Court overruled Grady and held that the same-elements test alone defines the “same offense,” in both the multiple-punishment and the successive-prosecution settings. Id. at 696, 704. The consequence matters for defense strategy: two charges can rest on one incident — the same night, the same victim, the same police report — and still be separate offenses, so long as each statute demands proof of an element the other lacks.

Because the analysis is element-driven, the tool asks you to enter statutory elements rather than the story of what happened. A description of the conduct (“he drove while intoxicated and hurt someone”) will not tell a court whether intoxication assault and DWI are the same offense; a side-by-side list of their elements will. When you run the comparison, keep each line to a discrete element — the act, the required mental state, the result, and any aggravating circumstance the statute names — so the match reflects the law rather than the narrative.

Keep in mind that whether two differently worded elements are legally “the same” can itself be litigated. Courts sometimes treat an element proved by an alternative theory as equivalent to another, which is why the tool’s text match is a first read, not a ruling.

Lesser-Included Offenses

When every element of one offense is also required by another, the smaller crime is a lesser-included offense, and Blockburger treats the greater and the lesser as the same offense. A conviction or acquittal on one generally bars a later prosecution for the other.

The leading illustration is Brown v. Ohio, 432 U.S. 161 (1977). Ohio prosecuted a defendant for joyriding and then for auto theft arising from the same nine-day course of conduct. Because joyriding — operating a car without the owner’s consent — required no fact that auto theft did not, it was a lesser-included offense. The Court held that the Double Jeopardy Clause barred the successive prosecution, and that the order did not matter: greater-then-lesser and lesser-then-greater are equally forbidden. Id. at 168–69.

Brown added a practical warning. Prosecutors cannot escape the Clause by slicing one continuing offense into “temporal or spatial units” and charging each slice separately. Id. at 169. Whether conduct is one offense or many turns on how the statute defines the unit of prosecution — the subject of the Texas discussion below.

For the tester, a lesser-included relationship shows up as an empty “only in” column on one side: every element of the smaller offense already appears among the larger offense’s elements. When that happens, the tool reports the two as the same offense. If, instead, both columns contain a unique element, neither offense is contained in the other, and the two are distinct under Blockburger.

Multiplicity Versus Successive Prosecution

The Double Jeopardy Clause does three jobs. As the Court put it in North Carolina v. Pearce, 395 U.S. 711, 717 (1969), it protects against a second prosecution after acquittal, a second prosecution after conviction, and multiple punishments for the same offense. Two of those strands drive most pretrial motions.

The same-elements test supplies the answer in both rows. Dixon confirmed that “same offense” carries a single meaning; a court does not apply one definition to stacked counts and a looser one to a second trial. 509 U.S. at 696. So the tool’s output is equally relevant whether the concern is two counts in one indictment or two separate prosecutions.

The strands do differ in remedy and timing. A multiplicity problem is about punishment, so it can often be corrected at or after judgment by vacating the surplus conviction. A successive-prosecution problem is about being tried at all — the protected interest is avoiding the second trial — which is why it must be raised before jeopardy attaches in the second case, and why an adverse ruling can sometimes be appealed immediately.

The Texas Unit-of-Prosecution Overlay

Texas follows Blockburger, but with an important overlay for multiple-punishment claims. In Ervin v. State, 991 S.W.2d 804 (Tex. Crim. App. 1999), the Court of Criminal Appeals held that the same-elements test is a “useful tool” for reading legislative intent — but not the only tool. Id. at 814. The ultimate question is whether the Legislature intended to allow more than one punishment.

To answer it, Ervin lists non-exclusive factors, including whether the offenses:

• appear in the same statutory section;
• are phrased in the alternative;
• carry similar names and punishment ranges;
• share a common focus or gravamen, and whether that focus points to a single instance of conduct; and
• have a legislative history speaking to double jeopardy.

Closely related is the allowable unit of prosecution — how many separate offenses one course of conduct can generate under a single statute. Ervin embraced the principle that “in homicide cases, the units of prosecution are dead bodies, not theories of aggravation,” so one death supports one homicide conviction even when several theories fit. Id. at 810, 817. That is why manslaughter and intoxication manslaughter merged there: one victim, one punishable offense.

The Texas Constitution supplies an independent double-jeopardy protection, Tex. Const. art. I, sec. 14, which Texas courts generally read in step with the federal Clause. The practical takeaway: run the same-elements comparison first, then, for a Texas multiple-punishment claim, test the result against legislative intent and the statute’s unit of prosecution. A pair of charges that looks “separate” on elements can still be one offense if the Legislature meant a single punishment.

Where the Double-Jeopardy Motion Fits

The comparison the tool performs is the analytical core of several pretrial filings. Which one fits depends on the forum and on whether the concern is stacked counts or a second prosecution.

Texas — multiplicity

Raise it by exception to the form of the charging instrument or a motion to quash, heard at a pretrial setting under Tex. Code Crim. Proc. art. 28.01.

Texas — former jeopardy

Plead it as a special plea under Tex. Code Crim. Proc. art. 27.05; where the claim is that a second trial is barred outright, a pretrial writ of habeas corpus is the recognized vehicle, because the right is to avoid the trial itself.

Federal court

Raise a double-jeopardy defect before trial under Fed. R. Crim. P. 12(b)(3); an order denying the motion is generally appealable at once.

Whatever the label, the motion succeeds or fails on the same-elements analysis, sharpened by the lesser-included and unit-of-prosecution points above. A well-built filing sets the two charging instruments side by side, walks the court through the elements, and shows either that one offense is wholly contained in the other or that the Legislature intended a single punishment.

This tool is general legal information, not legal advice, and its text comparison does not decide any case. If you are facing two charges arising from one incident, the attorneys at L&L Law Group, PLLC can review the specific statutes and record. Call (972) 370-5060 or email info@landllawgroup.com.

The Case Law Behind This Tool

The controlling decisions this tool is built on—each verified against the published opinion. Holdings are neutral summaries of the law, not predictions about any case.