An error control decoder receives a received vector to be decoded. The decoder then calculates, as an error estimate, the Euclidean distance between a codeword choice and the received vector. The output error estimate is appropriately scaled and quantized in accordance with the particular code being processed by the decoder. The efficient Conway-Sloane algorithm is extended for use in connection with the decoding of shortened Golay codes. A modification is made to the generator matrix for the Golay code to produce a modified generator matrix that is unique for each shortened code. The modified generator matrix is then implemented in the Conway-Sloane algorithm to identify the best codeword for conversion to its corresponding information bits for output.