The 73rd Amendment recognizes Gram Sabha as a constitutional body. This means that all the development plans of the panchayat have to be approved by the Gram Sabha.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/role-gram-sabha-vs-gram-panchayat-panchayat-plan-experiences
[2] http://admin.indiaenvironmentportal.org.in/category/journal/panchayati-raj-update
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/gram-sabhas
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/panchayats
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/political-decentralisation
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/planning
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/india