The research explores the compatibility of syntactic characteristics of legal English and plain English. The paper analyses the competition of linguistic means of expression between plain English and legal English. To this end, the paper (1) explores the characteristics of legal writing and identifies syntactic features that cause comprehension problems; (2) analyses syntactic features and means of expression of plain English; (3) investigates the compatibility of the requirements for plain English with the characteristics of legal English. The research is based on the Treaty of Lisbon. The findings prove that although formal requirements for legal English are compatible with the requirements for plain English, there is a great difference between the means of expression of the two variations. Nevertheless, plain English principles allow appropriate user-friendly syntactic competitors for most complicated cases of syntax in legal writing.