The digitalization of information is transforming the way we live and creating many new busi- ness models. Digitalization is also taking place in the legal domain. Legal documents, such as contracts and general terms and conditions, are produced thousands of times a day due to nu- merous online contract generators, e-commerce platforms, banks and insurance companies. As a result, computer-aided legal reasoning has become an attractive research area. The purpose of this research is to investigate the applicability of active machine learning and binary legal text classification in order to detect sentences, providing a statement about the ineffectiveness of a clause.