Why is it important to learn meditation from a certified teacher?

The Transcendental Meditation technique is taught only by professionally trained teachers, certified by the non-profit Maharishi Foundation. To ensure that each student receives the practice in its purity, these certified instructors uphold the tested and proven system of teaching developed by Maharishi. In its “purity” means in its original effectiveness—nothing tampered with, nothing changed—exactly as taught by Maharishi and in accord with the timeless procedures of the Vedic tradition. This system of teaching guarantees maximum benefit for everyone learning today and for future generations.
When you learn the Transcendental Meditation technique from a certified TM teacher, you can benefit from the ongoing guidance, personal support, group meditations and continuing knowledge programs available in every TM Center. Certified TM teachers have access to all the educational resources that Maharishi made available for this purpose through his non-profit teaching organization. This support system is invaluable for effective, successful practice, and is offered for the rest of your life at no charge—at any TM Center in the world—after you have learned the Transcendental Meditation technique. 

What is "certification?"
As with many professions that involve rigorous training and development of specific skills, TM teachers, after being qualified as instructors by attending TM Teacher Training, are asked to attend periodic teacher workshops and refresher courses to maintain their professional certification. Many TM teachers attended their teacher training courses 30 or 40 years ago; the re-certification ensures that all of the precise procedures of teaching are being followed properly and that the teacher has the latest knowledge and resources to best serve everyone who learns the TM technique.