Hereditary peers form part of the Peerage in the United Kingdom. There are over seven hundred peers who hold titles that may be inherited. Formerly, most of them were entitled to a seat in House of Lords, but since the House of Lords Act 1999 only ninety-two are permitted to sit, although this reduction has been challenged in the European Court of Human Rights. Peers are called to the House of Lords with a writ of summons. A hereditary title is not necessarily a title of the peerage. For instance, baronets and baronetesses may pass on their titles, but they are not peers. Similarly, the holder of a non-hereditary title may still belong to the peerage, as evidenced by the case of the Prince of Wales and of life peers. Peerages may be created by means of letters patent, but the granting of new hereditary peerages has dwindled, with only five new hereditary peerages granted since 1964.