Guide

LOCUS, ASAM, MCG: the criteria behind BH determinations

Summary

No single national rule defines behavioral-health medical necessity; the payer's contract and the clinical criteria it has adopted do. For substance use, many plans require or reference the ASAM Criteria; for mental-health level of care, plans use systems like LOCUS, licensed tools such as MCG or InterQual, or their own policy. Federal parity law treats those criteria as a non-quantitative treatment limitation the plan must apply and document even-handedly.

By Gale Editorial · Updated 2026-07-26. Every figure cited to a dated source. How we write.

Whose criteria actually govern a behavioral review?

No single national definition governs. Behavioral-health medical necessity is decided by the payer's contract and the clinical criteria that plan has adopted, so the operative question is always which criteria your specific plan applies to this service. In practice a handful of criteria sets recur: the ASAM Criteria for substance use, level-of-care systems like LOCUS for mental health, licensed commercial tools such as MCG and InterQual, and each plan's own internal medical policy.

Criteria set	Mainly used for	Who maintains it
ASAM Criteria	Substance-use level of care	American Society of Addiction Medicine
LOCUS / CALOCUS / CASII	Mental-health level of care	American Association of Community Psychiatrists
MCG, InterQual	Commercial utilization review	Licensed commercial vendors
Plan medical policy	Plan-specific determinations	The health plan

Because the way a contract defines medical necessity varies, the durable move is to read your plan's definition and its named criteria before you argue about any one case.

The substance-use standard: the ASAM Criteria

For substance use disorders, the ASAM Criteria are the closest thing to a common standard. They provide a multidimensional assessment across dimensions such as withdrawal risk, medical and psychiatric conditions, readiness to change, and recovery environment, producing a level-of-care placement rather than a yes-or-no. Many payers and several states require or reference the ASAM Criteria for substance-use level-of-care decisions 1Ref 1American Society of Addiction Medicine (2023).The ASAM Criteria.That the ASAM Criteria are the multidimensional standard for substance-use level-of-care placement, required or referenced by many payers and states..

That makes documenting to its dimensions the practical way to support an authorization: address each dimension in your assessment, and tie the level of care you are requesting to the specific findings that place the client there. When a reviewer applies ASAM, an appeal that speaks the criteria's own language — dimension by dimension — is far stronger than one that asserts the client needs care without mapping to the framework the plan is using.

The mental-health side: LOCUS and the plan's own policy

On the mental-health side there is less standardization. Level-of-care systems such as LOCUS — the Level of Care Utilization System, with child and adolescent versions — score several dimensions into a recommended intensity of service, and many behavioral plans reference them for level-of-care decisions. Just as often, the plan applies its own published medical policy, which names the criteria it uses for a given service.

A large behavioral network, for instance, publishes the level-of-care and authorization criteria it applies on its provider portal 2Ref 2Optum Behavioral Health (2026).Provider Express.A behavioral network's provider portal as where it publishes the level-of-care and authorization criteria it applies (named example, not all payers).. The takeaway for a solo clinician is procedural: for any mental-health service that needs authorization, find out whether the plan is applying a named level-of-care system, a commercial criteria set, or its own policy, because that determines what your documentation has to demonstrate and in what language.

MCG and InterQual: the proprietary review tools

Many plans do not write their own criteria from scratch; they license commercial ones. MCG and InterQual are the two widely used proprietary criteria sets that utilization reviewers apply to decide whether a level of care is medically necessary. You generally cannot see the full criteria unless the plan shares the specific guideline it applied, which is why a request for the exact criterion used is a standard and reasonable step in any appeal.

A plan's published clinical policy will usually state which criteria set governs a service, and your contract obliges the plan to apply it consistently 3Ref 3Anthem (2026).Anthem Provider Policies.A payer's own published clinical policy naming the medical-necessity criteria it applies to a service (named example; the reader's contract controls).. When you receive a denial, ask for the specific criterion and the reviewer's rationale in writing. That language tells you precisely what the plan believes is missing, which converts an appeal from a general disagreement into a targeted response against a named standard.

The parity overlay: medical necessity as an NQTL

Parity law reframes all of this. Under the federal Mental Health Parity and Addiction Equity Act, the medical-necessity criteria a plan uses for behavioral health are a non-quantitative treatment limitation, which the plan must apply no more stringently than it applies criteria on the medical-surgical side, and must document in a comparative analysis available on request 4Ref 4U.S. Department of Labor (2026).Mental Health and Substance Use Disorder Parity.That federal parity law treats behavioral medical-necessity criteria as a non-quantitative treatment limitation applied no more stringently than medical-surgical criteria, documented in a comparative analysis available on request..

That analysis is the lever. If a plan applies a stricter behavioral level-of-care rule than its medical counterpart — tighter review, more frequent reauthorization, a narrower medical-necessity definition — that disparity is a parity problem you can raise, and it connects to the broader behavioral-health payment gap. Requesting the comparative analysis, or pointing a state or federal regulator toward the disparity, is how the parity framework turns an abstract right into pressure on a specific determination.

What to do before an authorization or appeal

Turn the criteria into an operating routine. Before a service that needs authorization, find out which criteria set your plan applies to it — the provider manual or medical policy names it — and document to that set's dimensions from the start. When care runs long, the same discipline supports it: showing medical necessity on paper against the named criteria is stronger than arguing session count.

Some behavioral models formalize this by requiring validated rating scales to track response, and building measurement into your notes gives a reviewer the objective signal the criteria increasingly expect 5Ref 5Centers for Medicare & Medicaid Services (2024).Behavioral Health Integration Services.That behavioral integration and collaborative-care models require validated rating-scale, measurement-based care — the objective signal that supports a medical-necessity determination.. For frequent care such as twice-weekly therapy, tie each session to the criteria and the treatment plan, and document why the intensity is necessary — not merely that it occurred — which is also how the psychotherapy code you choose withstands review 6Ref 6APA Services, Inc. (2025).Psychotherapy Codes for Psychologists.That documenting the medical necessity of a longer or more frequent psychotherapy session supports the CPT code chosen and its review..

Common questions

It depends on the plan and the service. For substance-use level of care, many payers require or reference the ASAM Criteria. For mental-health level of care, a plan may use LOCUS, a licensed tool like MCG or InterQual, or its own published policy. The provider manual or medical policy names which set applies, so check it before you request authorization.

Both are multidimensional level-of-care systems, but they cover different populations. The ASAM Criteria place substance-use care across dimensions such as withdrawal risk and recovery environment. LOCUS, with its child and adolescent versions, scores mental-health service intensity. A plan may require ASAM for substance use while applying LOCUS or its own criteria for mental-health determinations.

You can ask, and you generally should. Commercial criteria like MCG and InterQual are proprietary, so you will not see the full manual, but a plan applying them to your client should identify the specific criterion used on request. Getting that language is a standard first step in an appeal, because it tells you exactly what to document against.

Federal parity law treats behavioral medical-necessity criteria as a non-quantitative treatment limitation, meaning a plan cannot apply them more stringently than its medical-surgical criteria and must produce a comparative analysis on request. If a behavioral level-of-care rule is tougher than its medical counterpart, that gap is a parity concern you can raise with regulators.

Write to the criteria the plan applies. Tie the assessment, diagnosis, treatment-plan goals, and each session note to the dimensions the criteria set scores, and add validated rating-scale results where you can. Showing necessity against the named criteria, rather than defending a session count, is what holds up in utilization review and on appeal.

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References

1.American Society of Addiction Medicine (2023). The ASAM Criteria. American Society of Addiction Medicine. link ✓That the ASAM Criteria are the multidimensional standard for substance-use level-of-care placement, required or referenced by many payers and states.
2.Optum Behavioral Health (2026). Provider Express. Optum Behavioral Health. linkA behavioral network's provider portal as where it publishes the level-of-care and authorization criteria it applies (named example, not all payers).
3.Anthem (2026). Anthem Provider Policies. Anthem provider portal. link ✓A payer's own published clinical policy naming the medical-necessity criteria it applies to a service (named example; the reader's contract controls).
4.U.S. Department of Labor (2026). Mental Health and Substance Use Disorder Parity. U.S. Department of Labor (EBSA). linkThat federal parity law treats behavioral medical-necessity criteria as a non-quantitative treatment limitation applied no more stringently than medical-surgical criteria, documented in a comparative analysis available on request.
5.Centers for Medicare & Medicaid Services (2024). Behavioral Health Integration Services. CMS Medicare Learning Network (MLN909432). link ✓That behavioral integration and collaborative-care models require validated rating-scale, measurement-based care — the objective signal that supports a medical-necessity determination.
6.APA Services, Inc. (2025). Psychotherapy Codes for Psychologists. APA Services, Inc.. link ✓That documenting the medical necessity of a longer or more frequent psychotherapy session supports the CPT code chosen and its review.

https://www.gale.care/for-providers/par-medical-necessity-criteria-bh · 6 sources. Competitor details are cited to dated public sources and maintained as they change; figures are estimates, not commitments. Synthetic demonstration.

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