diff --git a/ApiCore-Backend/src/queens/queens.service.spec.ts b/ApiCore-Backend/src/queens/queens.service.spec.ts
index 357f633..62d84a5 100644
--- a/ApiCore-Backend/src/queens/queens.service.spec.ts
+++ b/ApiCore-Backend/src/queens/queens.service.spec.ts
@@ -1,4 +1,8 @@
-import { BadRequestException, NotFoundException } from '@nestjs/common';
+import {
+  BadRequestException,
+  ConflictException,
+  NotFoundException,
+} from '@nestjs/common';
 import { QueensService } from './queens.service';
 import { PrismaService } from '../prisma/prisma.service';
 import { AuditLogService } from '../audit/audit-log.service';
@@ -78,6 +82,17 @@ describe('QueensService', () => {
     ).rejects.toBeInstanceOf(NotFoundException);
   });
 
+  it('assignColony rejects a queen who is no longer available', async () => {
+    prisma.queen.findUnique.mockResolvedValue({
+      ...queen,
+      status: 'DECEASED',
+    });
+    await expect(
+      service.assignColony('queen-1', { colonyId: 'colony-1' }, 'user-1'),
+    ).rejects.toBeInstanceOf(ConflictException);
+    expect(prisma.colony.findUnique).not.toHaveBeenCalled();
+  });
+
   it('assignColony closes the previous queen history, sets currentQueenId, and opens a new history row', async () => {
     prisma.queen.findUnique.mockResolvedValue(queen);
     prisma.colony.findUnique.mockResolvedValue({
diff --git a/ApiCore-Backend/src/queens/queens.service.ts b/ApiCore-Backend/src/queens/queens.service.ts
index 1fe5c07..fe811d1 100644
--- a/ApiCore-Backend/src/queens/queens.service.ts
+++ b/ApiCore-Backend/src/queens/queens.service.ts
@@ -1,5 +1,6 @@
 import {
   BadRequestException,
+  ConflictException,
   Injectable,
   NotFoundException,
 } from '@nestjs/common';
@@ -154,6 +155,11 @@ export class QueensService {
     actingUserId: string,
   ): Promise<Queen> {
     const queen = await this.findById(id);
+    if (QUEEN_NO_LONGER_AVAILABLE_STATUSES.includes(queen.status)) {
+      throw new ConflictException(
+        `Queen ${id} is not available for assignment (status: ${queen.status}) - correct her status first if this was a mistake`,
+      );
+    }
     const colony = await this.prisma.colony.findUnique({
       where: { id: dto.colonyId },
     });