` :'Jehovah's Witnesses' is normally a proper noun, as the name of a religious denomination, and it functions here as adjectival modifier. This presentation is consistent with similar article titles as indicated in 's comment above. The name 'Jehovah's Witnesses' does not function here as the plural of 'Jehovah's Witness' but as the proper name of an organisation. The other articles mentioned above are not called ``Sikhs' practices`` or ``Buddhists' practices``; similarly, this article title employs the proper noun ``Jehovah's Witnesses`` (which functions in the singular) as an adjectival modifier of ``practices``. It is therefore not used here as a possessive.  `