diff --git a/CHANGES.md b/CHANGES.md
index 82840e26..f6585295 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -8,7 +8,7 @@ Features:
  - None yet
 
 Changes:
- - None yet
+ - Upgrade to CourtListener v4 API([380](https://github.com/freelawproject/recap/issues/380), [401](https://github.com/freelawproject/recap-chrome/pull/401))
  
 Fixes:
  - Corrected typo in build script, ensuring correct favicon path for Firefox releases([379](https://github.com/freelawproject/recap/issues/379), [397](https://github.com/freelawproject/recap-chrome/pull/397))
diff --git a/spec/ContentDelegateSpec.js b/spec/ContentDelegateSpec.js
index 107d9852..57212cfe 100644
--- a/spec/ContentDelegateSpec.js
+++ b/spec/ContentDelegateSpec.js
@@ -361,7 +361,9 @@ describe('The ContentDelegate class', function () {
     it('has no effect when on a docket query that has no RECAP', async function () {
       const cd = docketQueryContentDelegate;
       spyOn(PACER, 'hasPacerCookie').and.returnValue(true);
-      const mockResponse = {};
+      const mockResponse = {
+        results: []
+      };
       dispatchBackgroundFetch = jasmine.createSpy().and.resolveTo(mockResponse);
       await cd.handleDocketQueryUrl();
       const banner = document.querySelector('.recap-banner');
diff --git a/src/appellate/appellate.js b/src/appellate/appellate.js
index 8c3e0a1d..4127ba45 100644
--- a/src/appellate/appellate.js
+++ b/src/appellate/appellate.js
@@ -282,18 +282,13 @@ AppellateDelegate.prototype.handleAcmsDocket = async function () {
         pacer_case_id: this.pacer_case_id,
       },
     });
-
-    if (docketData.count === 0) {
-      console.warn('RECAP: Zero results found for docket lookup.');
-    } else if (docketData.count > 1) {
-      console.error(
-        'RECAP: More than one result found for docket lookup. Found' +
-          `${result.count}`
-      );
-    } else {
+    let docketDataCount = docketData.results.length;
+    if (docketDataCount == 1){
       addAlertButtonInRecapAction(this.court, this.pacer_case_id);
       let cl_id = getClIdFromAbsoluteURL(docketData.results[0].absolute_url);
       addSearchDocketInRecapAction(cl_id);
+    } else{
+      PACER.handleDocketAvailabilityMessages(docketDataCount);
     }
   };
 
@@ -654,7 +649,8 @@ AppellateDelegate.prototype.handleDocketReportFilter = async function () {
       docket_number_core: docketNumberCore,
     },
   });
-  if (docketData.count === 1 && docketData.results) {
+  let docketDataCount = docketData.results.length;
+  if (docketDataCount === 1) {
     let form = document.getElementsByTagName('form')[0];
     let banner = recapBanner(docketData.results[0]);
     form.after(banner);
@@ -667,7 +663,7 @@ AppellateDelegate.prototype.handleDocketReportFilter = async function () {
     );
     form.after(recapAlert);
   } else {
-    PACER.handleDocketAvailabilityMessages(docketData);
+    PACER.handleDocketAvailabilityMessages(docketDataCount);
   }
 };
 
@@ -713,7 +709,8 @@ AppellateDelegate.prototype.handleCaseSelectionPage = async function () {
         pacer_case_id: this.pacer_case_id,
       },
     });
-    if (appellateData.count === 1 && appellateData.results) {
+    let appellateDataCount = appellateData.results.length;
+    if (appellateDataCount == 1) {
       PACER.removeBanners();
 
       const footer = document.querySelector('div.noprint:last-of-type');
@@ -728,7 +725,7 @@ AppellateDelegate.prototype.handleCaseSelectionPage = async function () {
       const appellateLink = anchors[0];
       rIcon.insertAfter(appellateLink);
     } else {
-      PACER.handleDocketAvailabilityMessages(appellateData);
+      PACER.handleDocketAvailabilityMessages(appellateDataCount);
     }
 
     if (anchors.length == 3) {
@@ -743,13 +740,14 @@ AppellateDelegate.prototype.handleCaseSelectionPage = async function () {
           docket_number_core: districtLinkData.docket_number_core,
         },
       });
-      if (districtData.count === 1 && districtData.results) {
+      let districtDataCount = districtData.results.length;
+      if (districtDataCount == 1) {
         const rIcon = APPELLATE.makeRButtonForCases(
           districtData.results[0].absolute_url
         );
         rIcon.insertAfter(districtLink);
       } else {
-        PACER.handleDocketAvailabilityMessages(districtData);
+        PACER.handleDocketAvailabilityMessages(districtDataCount);
       }
     }
   } else {
@@ -947,18 +945,13 @@ AppellateDelegate.prototype.handleDocketDisplayPage = async function () {
       pacer_case_id: this.pacer_case_id,
     },
   });
-
-  if (docketData.count === 0) {
-    console.warn('RECAP: Zero results found for docket lookup.');
-  } else if (docketData.count > 1) {
-    console.error(
-      'RECAP: More than one result found for docket lookup. ' +
-        `Found ${result.count}`
-    );
-  } else {
+  let docketDataCount = docketData.results.length;
+  if (docketDataCount === 1) {
     addAlertButtonInRecapAction(this.court, this.pacer_case_id);
     let cl_id = getClIdFromAbsoluteURL(docketData.results[0].absolute_url);
     addSearchDocketInRecapAction(cl_id);
+  } else {
+    PACER.handleDocketAvailabilityMessages(docketDataCount);
   }
 
   // if you've already uploaded the page, return
diff --git a/src/content_delegate.js b/src/content_delegate.js
index b106cb60..6ec45d9a 100644
--- a/src/content_delegate.js
+++ b/src/content_delegate.js
@@ -224,28 +224,22 @@ ContentDelegate.prototype.handleDocketQueryUrl = async function () {
     },
   });
 
-  if (docketData.count === 0) {
-    console.warn('RECAP: Zero results found for docket lookup.');
-  } else if (docketData.count > 1) {
-    console.error(
-      'RECAP: More than one result found for docket lookup. Found ' +
-        `${result.count}`
-    );
+  let docketDataCount = docketData.results.length;
+  if (docketDataCount === 1) {
+    PACER.removeBanners();
+    const dateToInput = document.querySelector('input[name=date_to]');
+    const form = document.querySelector('form');
+    const div = document.createElement('div');
+
+    div.classList.add('recap-banner');
+    div.appendChild(recapAlertButton(this.court, this.pacer_case_id, true));
+    form.appendChild(recapBanner(docketData.results[0]));
+    form.appendChild(div);
+
+    if (docketData.results[0].date_last_filing)
+      dateToInput.after(recapAddLatestFilingButton(docketData.results[0]));
   } else {
-    if (docketData.results) {
-      PACER.removeBanners();
-      const dateToInput = document.querySelector('input[name=date_to]');
-      const form = document.querySelector('form');
-      const div = document.createElement('div');
-
-      div.classList.add('recap-banner');
-      div.appendChild(recapAlertButton(this.court, this.pacer_case_id, true));
-      form.appendChild(recapBanner(docketData.results[0]));
-      form.appendChild(div);
-
-      if (docketData.results[0].date_last_filing)
-        dateToInput.after(recapAddLatestFilingButton(docketData.results[0]));
-    }
+    PACER.handleDocketAvailabilityMessages(docketDataCount);
   };
 };
 
@@ -297,19 +291,14 @@ ContentDelegate.prototype.handleDocketDisplayPage = async function () {
       pacer_case_id: this.pacer_case_id,
     },
   });
-  if (docketData.count === 0) {
-    console.warn('RECAP: Zero results found for docket lookup.');
-  } else if (docketData.count > 1) {
-    console.error(
-      'RECAP: More than one result found for docket lookup. Found ' +
-        `${result.count}`
-    );
-  } else {
+  let docketDataCount = docketData.results.length;
+  if (docketDataCount === 1) {
     addAlertButtonInRecapAction(this.court, this.pacer_case_id);
     let cl_id = getClIdFromAbsoluteURL(docketData.results[0].absolute_url);
     addSearchDocketInRecapAction(cl_id);
+  } else {
+    PACER.handleDocketAvailabilityMessages(docketDataCount);
   }
-
   // if you've already uploaded the page, return
   if (history.state && history.state.uploaded) return;
 
@@ -455,8 +444,7 @@ ContentDelegate.prototype.handleSingleDocumentPageCheck = async function () {
       pacer_doc_id__in: this.pacer_doc_id,
     },
   });
-
-  if (!recapLinks.count) return;
+  if (!recapLinks.results.length) return;
   console.info(
     'RECAP: Got results from API. Processing results to insert link'
   );
diff --git a/src/pacer.js b/src/pacer.js
index ae713076..3486beb0 100644
--- a/src/pacer.js
+++ b/src/pacer.js
@@ -740,11 +740,11 @@ let PACER = {
     return cleanNumber ? cleanNumber : 0;
   },
 
-  handleDocketAvailabilityMessages: (result) =>{
-    if (result.count === 0) {
+  handleDocketAvailabilityMessages: (resultCount) =>{
+    if (resultCount === 0) {
       console.warn('RECAP: Zero results found for docket lookup.');
-    } else if (result.count > 1) {
-      console.error(`RECAP: More than one result found for docket lookup. Found ${result.count}`);
+    } else if (resultCount > 1) {
+      console.error(`RECAP: More than one result found for docket lookup. Found ${resultCount}`);
     }
   },
 
diff --git a/src/utils/background_fetch.js b/src/utils/background_fetch.js
index 67e962d1..cf6d4c5a 100644
--- a/src/utils/background_fetch.js
+++ b/src/utils/background_fetch.js
@@ -11,7 +11,7 @@ import { buildFormData, sources, authHeader, jsonHeader } from './recap.js';
 // **Returns:**
 //  - A string representing the complete CourtListener API URL.
 const courtListenerURL = (suffix) =>
-  'https://www.courtlistener.com/api/rest/v3/' + suffix + '/';
+  'https://www.courtlistener.com/api/rest/v4/' + suffix + '/';
 
 // Encodes Search Parameters for GET Requests
 //