Spicer and the But-For Standard

Let us deal with the rumour first, because it is the reason most people arrive on this page.

The rumour appears to have grown out of a real event described badly. VA revised several M21-1 sections and, in doing so, removed the familiar phrase proximately due to from them. Screenshots of a manual section with long-standing language struck through are easy to misread, and a claim that "VA deleted secondary service connection" travels far faster than a correction. If you have been told your secondary claim is now pointless, you were told something that is not true.

What Spicer decided

Spicer v. McDonough was decided by the United States Court of Appeals for the Federal Circuit in March 2023. The court addressed how causation should be understood under 38 USC §1110, the statute that provides compensation for disability resulting from service, and adopted a but-for causation standard for that statutory language as it operates in the secondary service connection context.

But-for causation is an old and widely used legal test, and it asks one question:

Would the veteran have this second disability if the service-connected disability did not exist?

If the honest answer is no — the second condition would not have occurred but for the service-connected one — then the service-connected condition is a cause of it.

You can read the decision yourself through the Federal Circuit's opinions and orders database. We would rather you read the primary source than take our summary of it.

What the May 2026 M21-1 update did

Effective 1 May 2026, VA incorporated the Spicer framing into the M21-1, the manual its rating personnel work from. The affected parts include:

The M21-1 is guidance for VA employees. It is not a regulation. Under 38 CFR §19.5, the Board of Veterans' Appeals is expressly not bound by VA manuals — it is bound by statute, regulation, and precedential court decisions. That distinction matters more than it sounds, and we come back to it below. The current manual text is published on VA's KnowVA knowledge base.

What but-for causation means in practice

It handles causal chains

A but-for test travels naturally through more than one link. If a service-connected condition caused B, and B caused C, then C would not have occurred but for the service-connected condition — the chain holds as long as each link holds.

This is the same logic that underpins VA's own General Counsel opinion on obesity as an intermediate step, which was written in 2017 and framed its third question in explicitly but-for terms. To that extent, Spicer did not import something alien into VA practice. It made a standard VA was already using in one corner of the law into the general framing.

It supports treatment-interference theories

This is where a but-for standard is genuinely more generous, and it is worth understanding because these claims are rarely pleaded.

Suppose a service-connected condition does not cause a second disease at all, but it prevents that disease from being treated. A service-connected condition that rules out a surgery, contraindicates the standard medication, or makes a required therapy impossible to tolerate. Under a strict proximate-cause framing, VA might say the service-connected condition did not produce the second disease and stop there. Under a but-for framing, the question is different: without the service-connected condition, would this veteran be in the state they are in now? If the untreated deterioration would not have happened otherwise, the causal link is arguable.

It may cut the other way for ordinary secondaries

Here is the part that responsible commentators are worried about, and we are not going to pretend otherwise.

Many conditions VA sees in secondary claims are multifactorial — hypertension, obstructive sleep apnea, GERD, coronary artery disease. They have several contributing causes at once. Under a proximate-cause framing, an opinion could reasonably say the service-connected condition was a substantial contributing factor, and that has historically been enough. A strict but-for test can be read more narrowly: not merely that the service-connected condition contributed, but that the second condition would not have occurred at all without it. For a veteran with a family history of hypertension and service-connected PTSD, a rigid application of that test is harder to satisfy than the older phrasing.

Whether VA and the courts will apply but-for that rigidly, or read it alongside the established rule that a cause need not be the only cause, is not settled. There is a strong argument that the traditional multiple-cause principle survives Spicer intact, and there is a real argument that a blanket but-for standard raises the bar in ordinary cases even as it helps treatment-interference cases. Anyone telling you confidently which way this lands across the board is guessing. We will update this page as decisions accumulate.

What did not change

• The standard of proof. Spicer addressed the causation question, not the burden. 38 USC §5107(b) and 38 CFR §3.102 still apply: where the evidence for and against is in approximate balance, the benefit of the doubt goes to the veteran. The question is whether it is at least as likely as not that the second condition would not have occurred but for the service-connected one.
• The aggravation prong. §3.310(b) has its own analysis, with its own baseline-severity requirement. It is not a causation-of-onset question at all, so a causation standard does not straightforwardly transplant into it. How but-for interacts with aggravation has not been comprehensively worked out — see our aggravation page.
• Existing ratings. A secondary condition already service connected is not reopened by a manual revision. Ratings are protected by the rules in 38 CFR §3.344 and §3.951, not by which paragraph of the M21-1 was in force when they were granted.

Claims already pending at the Board

The Board decides an appeal under the law as it stands on the day of decision, and it is bound by Federal Circuit precedent whether or not the M21-1 has caught up. Practically:

1. Spicer applies to your pending appeal. It has, in fact, applied since 2023. The 2026 manual revision changed what regional office staff read, not what the Federal Circuit had already decided.
2. A pre-2026 medical opinion is not void. An opinion using the old phrasing is still evidence. But if it says only "at least as likely as not proximately due to," it may be worth obtaining a short addendum that also answers the but-for question in terms, so there is no gap for an adjudicator to fall into.
3. An examination that addressed only one prong is still inadequate. If the C&P examiner never reached aggravation, that failing predates Spicer and survives it. See inadequate C&P exams.

How to word an opinion now

Until the case law settles, the safe approach is an opinion that satisfies every formulation at once. When we request a medical opinion for a secondary claim, we ask the provider to address all three of these, each with reasoning:

• Whether it is at least as likely as not that the claimed condition would not have occurred but for the service-connected condition;
• Whether the service-connected condition was a substantial contributing factor in causing it; and
• Whether the service-connected condition aggravated it beyond its natural progression, and if so, what the baseline level of severity was before the aggravation began.

Three sentences. They cost the provider almost nothing to add, and they close the door on the most common ways a secondary claim gets denied. The nexus letter guide sets out the full structure.

The bottom line

Secondary service connection is alive. The causation question is now generally framed in but-for terms, which clearly helps some claims — particularly multi-step chains and cases where a service-connected condition is obstructing treatment — and may make some multifactorial claims harder to argue casually. The response is not to abandon the claim. It is to write the medical opinion so it answers the question in the form VA is now asking it.

If you were denied before the change, the denial is still reviewable on its own terms. Start with what to do when a VA claim is denied and choosing between HLR and a supplemental claim.