diff --git a/amendments.json b/amendments.json
index 21af09c14..5bf87432b 100644
--- a/amendments.json
+++ b/amendments.json
@@ -365,5 +365,25 @@
       "status": "candidate",
       "id": 25
     }
+  ],
+  "apply-local-description": [
+    {
+      "description": "Prune createAnswer()'s encodings and SendEncodings in sLD(answer).",
+      "pr": 2801,
+      "difftype": "modify",
+      "type": "correction",
+      "status": "candidate",
+      "id": 26
+    }
+  ],
+  "create-answer-restrictions": [
+    {
+      "description": "Prune createAnswer()'s encodings and SendEncodings in sLD(answer).",
+      "pr": 2801,
+      "difftype": "modify",
+      "type": "correction",
+      "status": "candidate",
+      "id": 26
+    }
   ]
 }
diff --git a/base-rec.html b/base-rec.html
index ab61b361e..c34fb8170 100644
--- a/base-rec.html
+++ b/base-rec.html
@@ -2773,7 +2773,7 @@ <h5 id="x4-4-1-5-set-the-session-description"><bdi class="secno">4.4.1.5 </bdi>
                               run the following steps for each <a data-link-type="dfn" href="#dfn-media-description" class="internalDFN" id="ref-for-dfn-media-description-2">media
                               description</a> in <var>description</var>:
                             </p>
-                            <ol>
+                            <ol id="apply-local-description">
                               <li>
                                 <p>
                                   If the <a data-link-type="dfn" href="#dfn-media-description" class="internalDFN" id="ref-for-dfn-media-description-3">media description</a> was not yet <a data-link-type="dfn" href="#dfn-associated" class="internalDFN" id="ref-for-dfn-associated-1">associated</a> with an <a data-link-type="idl" href="#dom-rtcrtptransceiver" class="internalDFN" id="ref-for-dom-rtcrtptransceiver-1"><code><code>RTCRtpTransceiver</code></code></a>
@@ -4512,7 +4512,7 @@ <h5 id="methods">
                         generate an SDP answer, <var>sdpString</var>, as
                         described in <span>[<cite><a class="bibref" data-link-type="biblio" href="#bib-rfc8829" title="JavaScript Session Establishment Protocol (JSEP)">RFC8829</a></cite>] (<a href="https://tools.ietf.org/html/rfc8829#section-5.3">section 5.3.</a>)</span>.
                       </p>
-                      <ol>
+                      <ol id="create-answer-restrictions">
                         <li>
                           <p>
                             The <i>codec preferences</i> of an m= section's
diff --git a/webrtc.html b/webrtc.html
index 301ff8230..42a054bf9 100644
--- a/webrtc.html
+++ b/webrtc.html
@@ -2134,7 +2134,7 @@ <h4>
                               run the following steps for each [= media
                               description =] in <var>description</var>:
                             </p>
-                            <ol>
+                            <ol id="apply-local-description">
                               <li>
                                 <p>
                                   If the [= media description =] was not yet [=
@@ -2259,6 +2259,35 @@ <h4>
                                   following steps:
                                 </p>
                                 <ol>
+                                  <li>
+                                    <p>
+                                      If <var>transceiver</var>.
+                                      {{RTCRtpTransceiver/[[Sender]]}}.{{RTCRtpSender/[[SendEncodings]]}}
+                                      .length is greater than <code>1</code>, then
+                                      run the following steps:
+                                    </p>
+                                    <ol>
+                                      <li>
+                                        <p>
+                                          If <var>description</var> is missing
+                                          all of the previously negotiated layers,
+                                          then remove all dictionaries in
+                                          <var>transceiver</var>.{{RTCRtpTransceiver/[[Sender]]}}.{{RTCRtpSender/[[SendEncodings]]}}
+                                          except the first one, and skip the next
+                                          step.
+                                        </p>
+                                      </li>
+                                      <li>
+                                        <p>
+                                          If <var>description</var> is missing any of
+                                          the previously negototiated layers, then
+                                          remove the dictionaries that correspond to
+                                          the missing layers from
+                                          <var>transceiver</var>.{{RTCRtpTransceiver/[[Sender]]}}.{{RTCRtpSender/[[SendEncodings]]}}.
+                                        </p>
+                                      </li>
+                                    </ol>
+                                  </li>
                                   <li>
                                     <p>
                                       Set
@@ -3977,7 +4006,7 @@ <h2>
                         described in <span data-jsep=
                         "generating-an-answer">[[!RFC8829]]</span>.
                       </p>
-                      <ol>
+                      <ol id="create-answer-restrictions">
                         <li>
                           <p>
                             The <i>codec preferences</i> of an m= section's
@@ -4023,17 +4052,33 @@ <h2>
                         </li>
                         <li>
                           <p>
-                            If the length of the {{RTCRtpSender/[[SendEncodings]]}} slot
-                            of the {{RTCRtpSender}} is larger than 1, then for
-                            each encoding given in {{RTCRtpSender/[[SendEncodings]]}} of
-                            the {{RTCRtpSender}}, add an <code class=
-                            "sdp">a=rid send</code> line to the corresponding
-                            media section, and add an <code class=
-                            "sdp">a=simulcast:send</code> line giving the RIDs
-                            in the same order as given in the
-                            {{RTCRtpSendParameters/encodings}} field. No RID
-                            restrictions are set.
+                            If this is an answer to an offer to receive
+                            simulcast, then for each media section requesting
+                            to receive simulcast, exclude from the media section
+                            in the answer any RID not found in the corresponding
+                            transceiver's
+                            {{RTCRtpTransceiver/[[Sender]]}}.{{RTCRtpSender/[[SendEncodings]]}}.
+                            If there are any identically named RIDs in the
+                            <code class="sdp">a=simulcast</code> attribute, remove all
+                            duplicates except the first one. No RID restrictions are set.
                           </p>
+                          <div class="note">
+                            <p>
+                              When a
+                              {{RTCPeerConnection/setRemoteDescription(offer)}}
+                              establishes a transceiver's [=simulcast envelope=],
+                              the transceiver's
+                              {{RTCRtpTransceiver/[[Sender]]}}.{{RTCRtpSender/[[SendEncodings]]}}
+                              is updated in
+                              {{RTCSignalingState/"have-remote-offer"}}. However,
+                              once a simulcast envelope has been established for
+                              the transceiver, subsequent pruning of the
+                              transceiver's
+                              {{RTCRtpTransceiver/[[Sender]]}}.{{RTCRtpSender/[[SendEncodings]]}}
+                              happen when this answer is set with
+                              {{RTCPeerConnection/setLocalDescription}}.
+                            </p>
+                          </div>
                         </li>
                       </ol>
                     </li>