In ESP (English for Specific Purposes) classes, it is generally beneficial for the instructor to have expertise in the field being taught. This is because ESP classes are designed to teach English language skills in a specific professional or academic context, and instructors who have experience in that context can provide relevant and authentic materials, activities, and feedback.
However, it is possible for instructors without direct experience in the field to still be successful in teaching ESP classes. In this case, the instructor would need to spend time researching the field, consulting with experts, and adapting materials and activities to ensure they are relevant and appropriate. They would also need to be aware of the language and communication needs of students in the field and tailor instruction accordingly.
In either case, the success of the instructor will depend on their ability to design and deliver effective instruction that meets the specific needs of the students. This includes selecting appropriate materials, creating engaging activities, providing targeted feedback, and fostering a supportive learning environment. Effective communication and interpersonal skills are also essential for building rapport with students and facilitating learning.
I am very grateful for your contribution about the discussion I have already raised about Esp teaching context. As you suggested, teaching ESP by non spe cialized teacher is not impossible but they need to develop their knowledge and competence to be familiar with each new field.