Maximum likelihood (ML) decoding of short constraint length convolutional codes became feasible with the invention of the Viterbi decoder. Several authors have since upper bounded the performance of ML decoders. A method to calculate the event error probability of an ML decoder for convolutional codes is described.
Schalkwijk, J. P. M., Post, K. A., & Aarts, J. P. J. C. (1979). On a method of calculating the event error probability of convolutional codes with maximum likelihood decoding. IEEE Transactions on Information Theory, 25(6), 737-743. https://doi.org/10.1109/TIT.1979.1056098