Res Gestae was defined in the case Vinod Kumar Baderbhai Patel v. State of Gujarat. Following was stated in the Judgement:
“Things did, or liberally speaking, the facts of the transaction explanatory of an act or showing a motive for acting; a matters incidental to a main fact and explanatory of it; including acts and words which are so closely connected with a main fact as will constitute a part of it, and without a knowledge of which the main fact might not be properly understood, even speaking for themselves though the instinctive words and acts of participants not the words and acts of participants when narrating the events, the circumstances, facts and declaration which grow out of the main fact, and contemporaneous with it and serve to illustrate its character or these circumstance which are the atomic and undersigned incidents of a particular litigated act and are admissible when illustrative of such act.”
In simple words it can be referred to the events, circumstances, remarks, etc. which relate to a particular case, especially as constituting admissible evidence in a court of law.
Indian Law Position
The maxim is widely recognized under the Indian Law.
State of Maharashtra v. Kamal Ahmed Mohd. Vakil Ansari & Ors. :
In the above-mentioned case honourable Supreme Court of India referred the doctrine of ‘Res Gestae’.
Dhal Singh Dewangan v. State Of Chhattisgarh:
In the above-mentioned case also honourable Supreme Court of India referred the doctrine of ‘Res Gesta’. 
Kyamuddin v. State:
In the above-mentioned case the doctrine of ‘Res Gesta’ was considered by the honourable Delhi High Court.
Edited by Vigneshwar Ramasubramania
Approved & Published – Sakshi Raje
 Vinod Kumar Baderbhai Patel v. State of Gujarat, 1998 INDLAW GUJ 22.
 State of Maharashtra v. Kamal Ahmed Mohd. Vakil Ansari & Ors., Criminal Appeal No.445 of 2013.
 Dhal Singh Dewangan v. State Of Chhattisgarh, Criminal Appeal No.(s).162-163 of 2014.
 Kyamuddin v. State, CRL.A. 602/2000.