Over the past decade, exponential growth of data in the legal industry has created a significant business challenge. Legal professionals are often overwhelmed by big data in cases: for example, every year docket data of over 350,000 cases are brought to courts in the United States and typical antitrust investigation cases involve reviewing and producing terabytes of data. This voluminous data must be processed and analyzed to derive new insights, better judgments, and effective strategies in legal cases. Artificial intelligence (AI) technologies, particularly natural language processing and machine learning, have been increasingly embraced by the legal industry to efficiently process and analyze large volume complex legal data and deliver legal services at reasonable costs and satisfactory speed.