Yes, you can file RTI application for deposition copies of a running court case from the concerned court. The Courts are Public Authority under section 2 (h) of RTI Act, 2005. All parties to a case in which a deposition is taken, as well as a deponent are entitled to obtain a copy of a deposition transcript. However, there are limitations on a third party's right to obtain a certified copy. Hence, application can be made u/s 2(f), 2(j) and 6 to concerned Public Information Officer with the payment of requisite fees as per RTI Act, 2005.
To file the application for the same please refer: https://onlinerti.com/apply