Previously “Merged” (Concurrent) Sentences Cannot Be “Unmerged” by Later Silence in a Subsequent Judgment

1. Introduction

Gillian v. Salmonsen (Mont. Sept. 8, 2026) is a Montana Supreme Court habeas corpus decision addressing whether the Department of Corrections (DOC) may reinterpret, and effectively restructure, the relationship between multiple sentences when later sentencing paperwork is silent about a sentence that was previously ordered to run concurrently (“merge”) with another sentence.

The petitioner, Rueben Gillian, accumulated several custodial sentences across multiple counties—Hill County (revocations), Powell County (escape), Lewis and Clark County (failure to register; assault on a peace officer). The respondent was the DOC official responsible for sentence calculation (Salmonsen). The core dispute was not whether Gillian had multiple valid sentences, but how those sentences were required to run together—concurrently or consecutively—and therefore what his correct custodial release/discharge date should be.

Gillian asserted all sentences ran concurrently and that DOC was holding him too long. DOC initially calculated a discharge date in 2029 by treating the failure-to-register sentence as consecutive to the other sentences, reasoning that a later judgment for assault on a peace officer did not mention the earlier failure-to-register sentence and thus implicitly “unmerged” it. The Court rejected that approach and ordered recalculation.

2. Summary of the Opinion

The Court granted Gillian’s petition for writ of habeas corpus under § 46-22-101(1), MCA, concluding that DOC’s sentence computation was erroneous. Although Gillian was wrong that he should have been released in December 2025, he established a facially invalid confinement basis because DOC calculated his discharge date by “unmerging” sentences that a district court had expressly merged.

The Court held that once the Lewis and Clark County District Court expressly ordered the failure-to-register sentence to “merge” (run concurrently) with the Powell County escape sentence as of December 1, 2022, that concurrency remained in place unless a court later specifically ordered a change. A subsequent judgment’s failure to mention the previously merged sentence did not convert it into a consecutive sentence by default.

The Court directed DOC and the Montana State Prison Records Bureau to recalculate Gillian’s sentences with all remaining custodial sentences running concurrently, yielding a custodial release date of September 5, 2027.

3. Analysis

A. Precedents Cited

Lott v. State, 2006 MT 279, § 20, 334 Mont. 270, 150 P.3d 337

The Court cited Lott v. State for the foundational function of habeas corpus in Montana: to remedy illegal imprisonment, including review of sentences for legality (e.g., whether the confinement exceeds lawful authority). Lott supports the Court’s willingness to entertain Gillian’s claim even though it concerned administrative sentence computation, because an incorrect computation can produce unlawful restraint.

Smith v. Salmonsen, No. OP 25-0289, 2025 Mont. LEXIS 515, Order (May 13, 2025)

DOC referenced Smith v. Salmonsen to explain “dead time” following escape—time an offender is not considered to be serving a custodial sentence because the offender is unlawfully at large. While not the main holding in Gillian, this citation framed DOC’s broader calculation practices and showed the Court’s awareness that sentence computation can include legally mandated exclusions.

Importantly, the Court’s ultimate ruling did not turn on “dead time”; it turned on whether DOC could restructure concurrent and consecutive relationships contrary to the judgments as properly interpreted.

State v. McGuire, 260 Mont. 386, 388, 860 P.2d 148, 150 (1993)

State v. McGuire provided a key constraint on sentencing power: “a sentencing court cannot impose a sentence consecutively to one not yet imposed.” The Court used McGuire to clarify the temporal scope of the Powell County escape judgment. When the escape sentence was imposed in September 2022 “consecutively to any underlying sentence,” the only “underlying” sentences it could lawfully be consecutive to were those already imposed at that time (the then-existing Hill County revocation sentences).

This mattered because DOC’s later approach effectively treated the failure-to-register sentence (imposed later, in December 2022) as if the September 2022 escape judgment could have dictated its relationship. The Court’s reliance on McGuire reinforces that sentence stacking must follow the sequencing and specificity of judicial pronouncements.

Hallberg v. Hughes, No. OP 21-0035, 2021 Mont. LEXIS 109, Order, at 3 (Feb. 2, 2021)

The Court cited Hallberg v. Hughes for the rule that an inmate must serve a custodial sentence before serving any probationary term. In Gillian, this helped the Court confirm the practical posture of the case: Gillian’s remaining time was custodial, not a question of when probation would begin. The principal dispute was therefore the correct custodial discharge date given concurrent-versus-consecutive alignment.

B. Legal Reasoning

The Court’s reasoning proceeds in three steps: (1) identify the governing statutory defaults for sentence structure; (2) interpret what the district courts actually ordered; and (3) reject DOC’s attempt to “fix” perceived ambiguity by altering the ordered structure.

1) Habeas corpus as the procedural vehicle

Under § 46-22-101(1), MCA, habeas relief is available where a person is illegally restrained. The Court treated an incorrect discharge date that extends custody beyond what the judgments authorize as a cognizable habeas problem—especially where, as here, the petitioner presented a “facially invalid sentence” calculation (i.e., the custody cannot be justified on the face of the judgments properly construed).

2) Default rule: consecutive unless otherwise ordered

The Court anchored its interpretation in § 46-18-401(4), MCA: “Separate sentences for two or more offenses must run consecutively unless the court otherwise orders.” This default gives sentencing courts the power to override consecutiveness with an express concurrency order.

3) The escape sentence was expressly consecutive (as to then-existing sentences)

The Powell County escape sentence stated it would run “consecutively to any underlying sentence,” and the Court also cited § 46-23-217, MCA (requiring consecutiveness when an inmate commits a crime while incarcerated). Thus, Gillian’s global claim that everything was concurrent failed as a matter of record.

But applying State v. McGuire, the Court limited what that consecutiveness could attach to: only sentences already imposed at the time of the escape sentencing.

4) The failure-to-register sentence was expressly merged with the escape sentence

In December 2022, the Lewis and Clark County District Court ordered that the failure-to-register sentence “shall merge” with the Powell County escape sentence (i.e., run concurrently). The Court treated that merger as a definitive judicial order under § 46-18-401(3), MCA (referenced by the Court when discussing concurrency authority).

5) Later silence does not undo an earlier express merger

The pivotal issue arose from the March 24, 2024 Lewis and Clark County judgment for assault on a peace officer. That judgment stated the new sentence would “merge with and run concurrently with” certain identified sentences, but it did not mention the earlier failure-to-register sentence. DOC argued this omission implied the court intended the failure-to-register sentence to become consecutive—effectively “unmerging” it from the escape sentence and stacking it after the other terms.

The Court rejected DOC’s interpretation. Once the failure-to-register sentence had been expressly merged with the escape sentence, it remained concurrent as of that date absent a later specific court order changing the relationship. The March 2024 judgment did not “specifically order any change,” so the prior merger remained operative. Accordingly, the assault sentence’s concurrency with the escape sentence necessarily placed it in concurrency with the failure-to-register sentence as well, because that sentence was already running concurrently with escape.

6) Administrative calculation must implement, not revise, judgments

DOC candidly explained that “the only way” it could honor all sentences was to “unmerge” and run failure-to-register consecutive to the others, producing a 2029 date. The Court’s response is the decision’s practical rule: administrative agencies must calculate time according to the lawful meaning of the judgments; they may not resolve silence or perceived conflicts by altering concurrency previously ordered by a court.

C. Impact

1) Limits on DOC discretion in sentence computation

The decision draws a bright operational line for DOC and prison records staff: when a sentencing court expressly orders concurrency (a “merge”), DOC cannot later treat that concurrency as undone merely because a subsequent judgment does not list every existing sentence. If the State or DOC believes a judgment is unclear or inconsistent, the appropriate remedy is to seek judicial clarification or amendment—not unilateral “unmerging.”

2) Greater stability in multi-sentence “stacking” across counties

Montana defendants frequently accumulate sentences from different judicial districts. Gillian reinforces that once one court merges a sentence with another, that relationship persists through later sentencings unless changed expressly. This promotes predictability for defendants, courts, and DOC in multi-county sentence matrices.

3) Guidance for sentencing judges and practitioners

The case implicitly encourages sentencing courts to be explicit when they intend to alter existing structures. For prosecutors and defense counsel, it underscores the importance of creating a clean record: if a court intends a later sentence to run consecutively to a sentence previously merged with another, it should say so plainly. Otherwise, earlier concurrency orders will control.

4. Complex Concepts Simplified

  • Concurrent vs. consecutive sentences: Concurrent sentences run at the same time; consecutive sentences run one after the other. Under § 46-18-401(4), MCA, consecutiveness is the default unless the court orders concurrency.
  • “Merge”: In this opinion, “merge” is used to mean a court-ordered concurrency instruction—one sentence runs together with another.
  • “Unmerge”: Not a formal statutory term here; DOC used it to describe treating a previously concurrent sentence as if it became consecutive later. The Court held DOC could not do that without an express judicial order.
  • Credit for time served: Days credited toward a sentence for time already spent in custody related to the offense/sentence.
  • “Dead time”: Time not counted toward service of a sentence, such as time unlawfully at large after escape (as described with reference to Smith v. Salmonsen).
  • Street time: Time spent out of custody while on probation; some revocation schemes may credit portions of it depending on the order and governing law (the opinion notes such an award in Gillian’s history).
  • Facially invalid sentence (in habeas context): A confinement justification that is demonstrably unlawful when measured against the judgments and governing law—here, an incorrect discharge date derived from an improper “unmerge.”

5. Conclusion

Gillian v. Salmonsen establishes a practical and administrable rule for Montana sentence calculation: an express judicial merger (concurrency) remains in effect unless a court later expressly changes it; later silence in a subsequent judgment does not “unmerge” sentences by default. Applying § 46-18-401(4), MCA’s default consecutiveness alongside the courts’ specific concurrency orders, the Montana Supreme Court held DOC’s 2029 discharge calculation unlawful and ordered recalculation to a September 5, 2027 custodial release date.