diff --git a/britney.py b/britney.py
index cf07c4d..b22d3b7 100755
--- a/britney.py
+++ b/britney.py
@@ -62,6 +62,9 @@ Other than source and binary packages, Britney loads the following data:
   * Hints, which contains lists of commands which modify the standard behaviour
     of Britney (see Britney.read_hints).
 
+  * Blocks, which contains user-supplied blocks read from Launchpad bugs
+    (see LPBlockBugPolicy).
+
 For a more detailed explanation about the format of these files, please read
 the documentation of the related methods. The exact meaning of them will be
 instead explained in the chapter "Excuses Generation".
@@ -210,7 +213,7 @@ from britney_util import (old_libraries_format, undo_changes,
                           create_provides_map,
                           ensuredir,
                           )
-from policies.policy import AgePolicy, RCBugPolicy, PolicyVerdict
+from policies.policy import AgePolicy, RCBugPolicy, LPBlockBugPolicy, PolicyVerdict
 
 # Check the "check_field_name" reflection before removing an import here.
 from consts import (SOURCE, SOURCEVER, ARCHITECTURE, CONFLICTS, DEPENDS,
@@ -538,6 +541,7 @@ class Britney(object):
 
         self.policies.append(AgePolicy(self.options, MINDAYS))
         self.policies.append(RCBugPolicy(self.options))
+        self.policies.append(LPBlockBugPolicy(self.options))
 
         for policy in self.policies:
             policy.register_hints(self._hint_parser)
diff --git a/policies/policy.py b/policies/policy.py
index e5222f1..bc7e50f 100644
--- a/policies/policy.py
+++ b/policies/policy.py
@@ -545,3 +545,50 @@ class RCBugPolicy(BasePolicy):
                 bugs[pkg] = set()
             bugs[pkg].update(l[1].split(","))
         return bugs
+
+
+class LPBlockBugPolicy(BasePolicy):
+    """block-proposed Launchpad bug policy for source migrations
+
+    This policy will read an user-supplied "Blocks" file from the unstable
+    directory (provided by an external script) with rows of the following
+    format:
+
+        <source-name> <bug> <date>
+
+    The dates are expressed as the number of seconds from the Unix epoch
+    (1970-01-01 00:00:00 UTC).
+    """
+    def __init__(self, options):
+        super().__init__('block-bugs', options, {'unstable'})
+
+    def initialise(self, britney):
+        super().initialise(britney)
+        self.blocks = {}  # srcpkg -> [(bug, date), ...]
+
+        filename = os.path.join(self.options.unstable, "Blocks")
+        self.log("Loading user-supplied block data from %s" % filename)
+        for line in open(filename):
+            l = line.split()
+            if len(l) != 3:
+                self.log("Blocks, ignoring malformed line %s" % line, type='W')
+                continue
+            try:
+                self.blocks.setdefault(l[0], [])
+                self.blocks[l[0]].append((l[1], int(l[2])))
+            except ValueError:
+                self.log("Blocks, unable to parse \"%s\"" % line, type='E')
+
+    def apply_policy_impl(self, block_bugs_info, suite, source_name, source_data_tdist, source_data_srcdist, excuse):
+        try:
+            blocks = self.blocks[source_name]
+        except KeyError:
+            return PolicyVerdict.PASS
+
+        for bug, date in blocks:
+            block_bugs_info[bug] = date
+            excuse.addhtml("Not touching package as requested in <a href=\"https://launchpad.net/bugs/%s\">bug %s</a> on %s" %
+                           (bug, bug, time.asctime(time.gmtime(date))))
+        excuse.addreason('block')
+
+        return PolicyVerdict.REJECTED_PERMANENTLY