Maine's Department of Corrections (MDOC) says it ended solitary confinement. People inside Maine's prisons say they are living in solitary confinement. The gap between those two positions is the defining story of solitary confinement in Maine -- and the reason the Maine Legislature has repeatedly tried, and repeatedly failed, to pass a bill simply defining what solitary confinement means.
The state's most restrictive housing is the Administrative Control Unit (ACU) at Maine State Prison in Warren. MDOC says the ACU is not solitary confinement -- residents can leave their cells for up to 4 hours per day, have access to programming, counseling, and television, and the unit houses a very small number of people. As of 2022, only 7 of Maine's approximately 1,600 state prison residents were in the ACU.
But incarcerated people and advocates have described units where people spend 21 or more hours per day in cells, where staffing shortages routinely prevent even the promised out-of-cell time, and where conditions bear every practical characteristic of solitary confinement even if MDOC refuses the label. In a 2024 letter obtained by Maine Morning Star, MDOC Commissioner Randall Liberty acknowledged that in the 8-day period one resident cited in a grievance, out-of-cell time fell below the stated goal multiple times due to staffing shortages.
The definitional dispute is not a technicality -- in Maine, without an agreed legal definition of solitary confinement, advocates and courts have no benchmark against which to measure conditions or enforce rights.
What Solitary Confinement Is Called in Maine
MDOC has used several terms over the years for its most restrictive housing:
Special Management Unit (SMU): The former term for Maine State Prison's most restrictive unit. Reformed significantly starting around 2011 under Commissioner Joseph Ponte. Widely acknowledged at the time as a dramatic reduction in solitary confinement use.
Administrative Control Unit (ACU): The current term for Maine State Prison's most restrictive housing. MDOC classifies ACU residents as "general population" and asserts that the ACU does not constitute solitary confinement. Residents can leave for 4 hours per day when staffing permits.
The renaming pattern has been noted explicitly by lawmakers. House Criminal Justice and Public Safety Committee Chair Rep. Charlotte Warren (D-Hallowell) said in 2022: "One of the things that we do know is that there have been frequent changes of the name. We asked questions about solitary confinement, they change it to 'restrictive housing.' We ask questions about 'restrictive housing,' then it has a new name."
Maine also has other forms of restricted housing including protective custody and administrative segregation for shorter-term placements.
Maine also has Title 34, Section 709 in Maine statute, which references disciplinary action and solitary confinement in jails -- one of the oldest statutory references to the practice in Maine law.
The Administrative Control Unit at Maine State Prison
The ACU is located at Maine State Prison in Warren (Knox County), Maine's only maximum-security prison for men. MDOC describes the ACU as housing for violent prisoners who pose a safety threat to themselves or others. Under MDOC's description:
- Residents can leave their cells for up to 4 hours per day.
- They have access to educational programming and counseling.
- They have access to television.
- Placement requires a disciplinary finding and finding of a serious act of violence or threat.
As of 2022, only 7 of Maine's approximately 1,600 state prison residents were in the ACU. MDOC has presented this low number as evidence that the ACU is used sparingly and responsibly.
However, incarcerated people and their advocates have described other housing units -- not formally designated as ACU -- where people experience conditions indistinguishable from solitary confinement, including extended cell time and severe restrictions. The absence of a legal definition means there is no statutory framework for evaluating whether conditions in other housing units constitute solitary confinement.
Who Can Be Placed in the ACU
MDOC policy requires a disciplinary finding and a finding of a serious act of violence or a threat before an ACU placement. This is a higher bar than many states, which allow administrative segregation without a prior disciplinary hearing.
For housing units that are not formally designated as ACU -- where incarcerated people describe solitary-like conditions -- the placement criteria are less clearly defined and less publicly documented.
Conditions in Maine's ACU
Under MDOC's description: up to 4 hours out of cell per day; programming, counseling, and TV access; single-person cells. However, the April 2024 letter from Commissioner Liberty to a grievant acknowledged that in an 8-day period, residents in one recreation group received between 1.5 and 2.5 hours out of cell per day -- below the stated 2.5-hour goal -- due to staffing shortages.
MDOC's goal of 2.5 hours per day (which it sometimes does not meet) is still well below the 4 hours per day that MDOC has cited in public-facing descriptions of the ACU. This gap -- between the stated policy and the documented practice -- is part of what drives advocates' insistence that legislation defining and regulating solitary is necessary.
The Definition Dispute and Legislative History
From 2010 forward, Maine advocates and legislators have repeatedly tried to establish a statutory definition of and limits on solitary confinement:
2010: LD 1611 (An Act to Ensure Humane Treatment of Special Management Prisoners) passed both houses of the Maine Legislature in amended form. ACLU of Maine described it as mirroring much of current DOC policy and establishing 8th Amendment protections in statute.
2022: LD 696 passed the Maine House. Defined solitary as confinement in a cell for over 22 hours per day. Did not become law amid continuing disagreements.
2023-2024: LD 1086 (Rep. Grayson Lookner, D-Portland) would have defined solitary confinement as isolation for 22 hours or more per day. The Criminal Justice and Public Safety Committee split three ways. Bill died at the end of the 131st Legislature (December 4, 2024).
132nd Legislature (2025-2026): New LD 696 introduced to prohibit solitary confinement. Maine was listed by the Unlock the Box Campaign as one of twelve states to pass solitary confinement legislation between July 2024 and July 2025. Verify what specifically passed in the 132nd Legislature at publish.
Mental Health Protections
Maine's 2010 LD 1611 included provisions that, according to the ACLU of Maine, would "enshrine in Maine law, the 8th Amendment protections which bar placement of serious mentally ill prisoners in the SMU." Whether and how those protections have been maintained through the subsequent renaming of units should be verified at publish.
MDOC operates under general Eighth Amendment mental health care obligations. Maine's relatively small prison population (roughly 1,600-2,000 people in state facilities) means there is a single maximum-security facility where the most restrictive housing is concentrated.
What Families Can Do
If your person is in the ACU or another restricted housing unit in a Maine state prison:
Find where your person is housed. MDOC provides an offender search at maine.gov/corrections. This confirms current facility placement.
Contact Maine State Prison directly. The ACU is at Maine State Prison in Warren. Contact MSP's administrative staff through MDOC's contact directory to confirm your person's housing status, the stated reason for any restricted placement, and current visiting and communication rules.
Ask about out-of-cell time. Under MDOC's own stated goal, ACU residents should receive 2.5 hours out of cell per day. If your person is receiving significantly less, this is a condition worth documenting and raising through the grievance process.
Document everything. If your person is in a housing unit with restricted out-of-cell time -- whether formally ACU or not -- keep records of every contact: cell time reported, programming access, mental health visits, visit and phone access.
File a grievance. MDOC has an administrative grievance process. Commissioner Liberty responded directly to the grievance in the April 2024 letter -- the process does function. Help your person file formal grievances documenting conditions.
Contact the ACLU of Maine. The ACLU of Maine (aclumaine.org) has been the lead advocacy organization on Maine solitary confinement reform for decades and may be able to provide referrals or current information.
Contact the Maine Prisoner Advocacy Coalition. MPAC (maineprisoneradvocacy.org) has been active in pushing for solitary reform legislation and may provide advocacy support and referrals.
Seek legal help. If your person has a serious mental illness and is in conditions that amount to solitary confinement without adequate mental health care, this may give rise to Eighth Amendment claims. The definitional dispute makes litigation more complex in Maine -- consult a prisoner rights attorney familiar with Maine federal courts.
Frequently asked questions
Does Maine use solitary confinement in its prisons?
MDOC says no -- it claims it ended solitary confinement and its most restrictive housing, the Administrative Control Unit (ACU) at Maine State Prison, is not solitary because residents can leave for up to 4 hours per day. Incarcerated people and advocates dispute this, describing conditions in the ACU and other housing units that are functionally indistinguishable from solitary. The absence of a legal definition means there is no statutory standard against which to evaluate the claim.
What is the Administrative Control Unit in Maine?
The ACU is Maine State Prison's most restrictive housing unit, located in Warren. MDOC reserves it for violent prisoners who pose a safety threat. Under MDOC's description, residents can leave for up to 4 hours per day (2.5 hours is the stated goal), have programming and TV access, and can receive counseling. As of 2022, only 7 of approximately 1,600 state prison residents were in the ACU. A 2024 MDOC letter acknowledged the 2.5-hour daily goal was not always being met due to staffing shortages.
Why does Maine dispute what counts as solitary confinement?
MDOC has consistently argued that its housing practices do not meet the definition of solitary confinement because residents have some out-of-cell time and programming access. Advocates counter that the conditions -- extended cell confinement, isolation from general population -- are functionally solitary regardless of the label. The Legislature has repeatedly tried and failed to pass a statutory definition. Legislators have noted that MDOC has changed its terminology repeatedly as scrutiny mounted: SMU became restrictive housing, which became the Administrative Control Unit, which MDOC categorizes as general population.
Who can be placed in the ACU at Maine State Prison?
MDOC policy requires a disciplinary finding and a finding of a serious act of violence or threat before placement in the ACU. This is more restrictive than many states, which allow administrative segregation without a prior disciplinary hearing. For other housing units where incarcerated people describe solitary-like conditions, placement criteria are less clearly defined publicly.
What are conditions like in Maine's ACU?
Under MDOC's description: single cells, up to 4 hours out per day (2.5-hour daily goal), programming access, TV, counseling. In practice, a 2024 MDOC Commissioner letter acknowledged that in one 8-day period, out-of-cell time fell between 1.5 and 2.5 hours per day due to staffing shortages -- below even the 2.5-hour stated goal. Incarcerated people and advocates have described conditions in the ACU and other units as functionally identical to solitary confinement.
How long can someone stay in Maine's ACU?
Maine has no statute limiting the duration of ACU placement. MDOC's disciplinary finding requirement means placement is tied to a specific finding, but the ongoing duration is controlled by MDOC's review process. Under MDOC's policies, placement is reviewed periodically. MDOC has not published public data on average ACU duration or length of stay.
Are mentally ill prisoners protected from solitary in ME?
Maine's 2010 legislation (LD 1611) included provisions designed to protect seriously mentally ill prisoners from placement in the most restrictive housing under 8th Amendment standards. MDOC's general mental health care obligations also apply. There is no current statute with a specific SMI-protection framework as robust as Colorado, Connecticut, or Arizona. The ACLU of Maine is the resource for current information on enforcement of mental health protections in MDOC restrictive housing.
What legislation has Maine passed on solitary confinement?
Maine has struggled to pass comprehensive legislation. LD 1611 (2010) established some protections. Multiple subsequent efforts -- including LD 696 (2022, passed House only), LD 1086 (2023-2024, died), and new LD 696 (2025) -- have either failed or remained pending. Maine was listed by the Unlock the Box Campaign as one of twelve states to pass solitary confinement legislation between July 2024 and July 2025. Verify what specifically passed in the 132nd Legislature at publish.
Can families visit someone in Maine's ACU?
Visiting during ACU placement may be restricted. Contact Maine State Prison directly to confirm current visiting rules before traveling. MDOC facility contact information is at maine.gov/corrections. Written mail generally retains stronger protections than phone or visits during restricted housing.
What can families do if someone is isolated in ME prison?
Use MDOC's offender search at maine.gov/corrections to find your person. Contact Maine State Prison in Warren to confirm housing status and stated reason for restricted placement. Ask specifically about daily out-of-cell time and compare to MDOC's stated 2.5-hour goal. Document conditions and file grievances through MDOC's process. Contact the ACLU of Maine (aclumaine.org) or Maine Prisoner Advocacy Coalition (maineprisoneradvocacy.org) for advocacy support and referrals. ---