The article examines how standard contract terms as used in contractual practice have influenced the development of the law. It is structured in two parts. The first part summarises the function of general contract terms in today's world and highlights the role of contract lawyers for the advancement of private and commercial law. The second part analyses in comparative perspective the interplay between contractual practice and the traditional forces shaping the law (legislators, courts and professors). It is demonstrated that, on the one hand, the legislature embraced some of the standards established by contractual practice, as for example newly developed types of contracts were later codified. On the other hand, the legislature had to react to eliminate unfair contract terms. It therefore first enacted isolated mandatory rules before establishing a set of general rules for identifying and prohibiting unfair contract terms. Within Europe, there are still significant differences as to the scope of these general rules, mainly with regard to the mechanism for the control of unfair terms in contracts between businesses. Once a full-fledged general set of rules is enacted by the legislature, the legal framework remains rather stable, as it is based to a large part on general clauses. These clauses must be applied and interpreted by the courts. Shaping the law of unfair contract terms by interpreting general clauses is the main task of judges today. Historically, however, it fell to the judges to advance the law of unfair contract terms as a reaction to standard clauses developed by contract lawyers. Many rules today enshrined in statutory form were developed by private law adjudication. Finally, the relationship of contractual practice and the academic world is discussed. Scholars mainly focus on the case law addressing unfair contractual terms. They advance the law by shaping the (European) foundations of unfair contract terms law, by systemising the case law and by diagnosing reforms to be effected by the courts or by the legislature.