diff --git a/app/controllers/ajax/moderation_controller.rb b/app/controllers/ajax/moderation_controller.rb
index 8bd822e6..f2149885 100644
--- a/app/controllers/ajax/moderation_controller.rb
+++ b/app/controllers/ajax/moderation_controller.rb
@@ -109,13 +109,15 @@ class Ajax::ModerationController < AjaxController
     params.require :user
     params.require :ban
     params.require :permaban
+    params.require :duration
+    params.require :duration_unit
 
-    reason = params[:reason]
+    duration = params[:duration].to_s
+    duration_unit = params[:duration_unit].to_s
+    reason = params[:reason].to_s
     target = User.find_by_screen_name!(params[:user])
-    unban  = params[:ban] == "0"
-    perma  = params[:permaban] == "1"
-
-    buntil = DateTime.strptime params[:until], "%m/%d/%Y %I:%M %p" unless unban || perma
+    unban  = params[:ban] == '0'
+    perma  = params[:permaban] == '1'
 
     if !unban && target.has_role?(:administrator)
       @response[:status] = :nopriv
@@ -128,11 +130,11 @@ class Ajax::ModerationController < AjaxController
       @response[:message] = I18n.t('messages.moderation.ban.unban')
       @response[:success] = true
     elsif perma
-      target.ban nil, reason
+      target.ban nil, nil, reason, current_user
       @response[:message] = I18n.t('messages.moderation.ban.perma')
     else
-      target.ban buntil, reason
-      @response[:message] = I18n.t('messages.moderation.ban.temp', date: buntil.to_s)
+      target.ban duration, duration_unit, reason, current_user
+      @response[:message] = "User banned for #{duration} #{duration_unit}"
     end
     target.save!
 
@@ -162,7 +164,7 @@ class Ajax::ModerationController < AjaxController
 
     @response[:checked] = status
     type = params[:type].downcase
-    target_role = {"admin" => "administrator"}.fetch(type, type).to_sym
+    target_role = {'admin' => 'administrator'}.fetch(type, type).to_sym
 
     if status
       target_user.add_role target_role
diff --git a/app/models/user.rb b/app/models/user.rb
index 0c23c4cd..bbcc8f6b 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -223,21 +223,24 @@ class User < ApplicationRecord
   end
   # endregion
 
-  # forwards fill
   def banned?
-    self.permanently_banned? or ((not self.banned_until.nil?) and self.banned_until >= DateTime.current)
+    self.user_bans.current.any?
   end
 
   def unban
-    self.update(permanently_banned: false, ban_reason: nil, banned_until: nil)
+    self.user_bans.current.update(expires_at: DateTime.now)
   end
 
-  def ban(buntil=nil, reason=nil)
-    if buntil == nil
-      self.update(permanently_banned: true, ban_reason: reason)
-    else
-      self.update(permanently_banned: false, banned_until: buntil, ban_reason: reason)
-    end
+  # Bans a user.
+  # @param duration [Fixnum, nil] Ban duration
+  # @param duration_unit [String, nil] Unit for the <code>duration</code> parameter. Accepted units: hours, days, weeks, months
+  # @param reason [String] Reason for the ban. This is displayed to the user.
+  # @param banned_by [User] User who instated the ban
+  def ban(duration, duration_unit = 'hours', reason = nil, banned_by = nil)
+    raise Errors::InvalidBanDuration unless %w[hours days weeks months].include? duration_unit
+
+    expiry = duration && DateTime.now + duration.public_send(duration_unit)
+    self.user_bans.create(expires_at: expiry, reason: reason, banned_by: banned_by)
   end
 
   def can_export?
diff --git a/app/models/user_ban.rb b/app/models/user_ban.rb
index ee143412..e7b3c1fe 100644
--- a/app/models/user_ban.rb
+++ b/app/models/user_ban.rb
@@ -1,4 +1,6 @@
 class UserBan < ApplicationRecord
   belongs_to :user
   belongs_to :banned_by, class_name: 'User'
+
+  scope :current, -> { where('expires_at IS NULL or expires_at < NOW()') }
 end
diff --git a/lib/errors.rb b/lib/errors.rb
new file mode 100644
index 00000000..c13228a8
--- /dev/null
+++ b/lib/errors.rb
@@ -0,0 +1,7 @@
+module Errors
+  class Base < StandardError
+  end
+
+  class InvalidBanDuration < Base
+  end
+end
\ No newline at end of file