diff --git a/scripts/license-headers.py b/scripts/license-headers.py
index b36b92a8..bbf32fc6 100644
--- a/scripts/license-headers.py
+++ b/scripts/license-headers.py
@@ -27,19 +27,29 @@ HEADER_LINES = (
 )
 
 
-_SPDX_RE = re.compile(r"SPDX-License-Identifier:\s*(\S+)")
 _CMSD_ID = "LicenseRef-CMSD-1.0"
+# Matches an SPDX line only when preceded by comment markers and/or
+# whitespace. Prevents false-matches when a docstring mentions the
+# token "SPDX-License-Identifier:" in prose.
+_SPDX_LINE_RE = re.compile(
+    r"^[\s/*#<!\->]*\s*SPDX-License-Identifier:\s*(\S+)"
+)
 
 ENROLLMENT_FILE = "scripts/license-headers-enrolled.txt"
 
 
 def detect_existing(text: str) -> str:
-    """Return 'MATCH', 'FOREIGN', or 'NONE' based on the first 10 lines."""
-    head = "\n".join(text.splitlines()[:10])
-    match = _SPDX_RE.search(head)
-    if not match:
-        return "NONE"
-    return "MATCH" if match.group(1) == _CMSD_ID else "FOREIGN"
+    """Return 'MATCH', 'FOREIGN', or 'NONE' based on the first 10 lines.
+
+    Only lines whose non-whitespace content begins with comment markers
+    (#, //, *, <!--, -->) and then an SPDX identifier count as a license
+    declaration. Prose mentions inside docstrings are ignored.
+    """
+    for line in text.splitlines()[:10]:
+        match = _SPDX_LINE_RE.match(line)
+        if match:
+            return "MATCH" if match.group(1) == _CMSD_ID else "FOREIGN"
+    return "NONE"
 
 
 def render_header(style: str) -> str:
@@ -235,9 +245,16 @@ def _find_repo_root(start: Path) -> Path:
 
 
 def _read_enrollment(repo_root: Path) -> list[str]:
+    """Return enrollment patterns from scripts/license-headers-enrolled.txt.
+
+    Phase semantics (per spec §5.2):
+      * Missing file → ["**"]  — repo-wide enforcement (Phase C final state)
+      * File exists, empty / only comments → []  — nothing enforced (Phase A initial)
+      * File with patterns → those patterns
+    """
     f = repo_root / ENROLLMENT_FILE
     if not f.exists():
-        return []
+        return ["**"]
     patterns: list[str] = []
     for raw in f.read_text().splitlines():
         line = raw.strip()
diff --git a/tests/test_license_headers.py b/tests/test_license_headers.py
index b485ceaa..1e99bfad 100644
--- a/tests/test_license_headers.py
+++ b/tests/test_license_headers.py
@@ -120,6 +120,29 @@ def test_detect_existing_only_checks_first_10_lines():
     assert license_headers.detect_existing(text) == "NONE"
 
 
+def test_detect_existing_no_false_match_in_docstring():
+    """Prose mentions of SPDX inside docstrings/comments should NOT match.
+
+    Regression: previously the regex matched any 'SPDX-License-Identifier:'
+    token anywhere in the first 10 lines, including inside Python docstrings
+    that *describe* what an SPDX header looks like.
+    """
+    text = (
+        '"""License header tool.\n'
+        '\n'
+        'Adds the SPDX-License-Identifier: LicenseRef-CMSD-1.0 header.\n'
+        '"""\n'
+        'x = 1\n'
+    )
+    assert license_headers.detect_existing(text) == "NONE"
+
+
+def test_detect_existing_no_false_match_inline_comment_prose():
+    """`# Description mentioning SPDX-License-Identifier: ...` is NOT a license line."""
+    text = "# This module documents SPDX-License-Identifier: MIT compliance.\nx = 1\n"
+    assert license_headers.detect_existing(text) == "NONE"
+
+
 def test_apply_python_plain():
     src = '"""Docstring."""\nprint("hi")\n'
     out = license_headers.apply(src, ".py")
@@ -422,3 +445,19 @@ def test_main_empty_allowlist_passes_check(tmp_path, monkeypatch):
     monkeypatch.chdir(tmp_path)
     rc = license_headers.main(["--check"])
     assert rc == 0
+
+
+def test_read_enrollment_missing_file_means_repo_wide(tmp_path):
+    """Spec §5.2: missing allowlist file = repo-wide enforcement (Phase C final)."""
+    assert license_headers._read_enrollment(tmp_path) == ["**"]
+
+
+def test_main_check_missing_allowlist_enforces_repo_wide(tmp_path, monkeypatch):
+    """With no allowlist file present, --check should fail on any unheadered file."""
+    (tmp_path / ".git").mkdir()
+    (tmp_path / "scripts").mkdir(exist_ok=True)
+    # No enrollment file written.
+    (tmp_path / "a.py").write_text("x = 1\n")  # no header
+    monkeypatch.chdir(tmp_path)
+    rc = license_headers.main(["--check"])
+    assert rc == 1