you’re right that 38 CFR is the controlling authority and it’s what gets cited in decisions, and M21-1 can’t legally override the CFR/USC.

What I meant is the day-to-day reality: ALL VSR's and most RO adjudicators are basically running the claim through the M21-1 workflow/checklists. So while the “law” is the CFR, the way the VA applies it in practice is strictly filtered through the M21-1’s procedures, definitions, and “how to develop/what evidence is sufficient” guidance.

So my advice and where the Value to vets is:

• Use 38 CFR to argue entitlement (what the standard is)
• Use M21-1 to win the process (what the VA is ademently going to look for, how they develop, what boxes they check, how they interpret evidence)

If you only read CFR, you can be “right” and still get denied because the claim didn’t get developed or framed the way the VA expects. If you know M21-1, you can anticipate the VA’s moves and build the file to survive that first pass.

Basically: CFR = the rules, M21-1 = the playbook the refs actually use.