Doctors owe a legal duty of care to patients, of which legal standard of care, especially on advice, evolves over time. With the modified Montgomery test, informed consent involves a process of best interests decision-making accompanied by disclosure of relevant information in a comprehensible fashion, to the patient. Ethical issues confronting treatment decision and advice are also manifold and have to be confronted. For example, in amyotrophic lateral sclerosis (ALS), an incurable disease, death is usually due to respiratory failure. Tracheostomy ventilation (TV) may be the only alternative to death, yet patients on TV may be subject to the relentless progression of ALS resulting in a locked-in state. Through a case vignette of invasive ventilation for ALS, we examine the ethical and legal issues regarding choice of assisted ventilation in these patients, especially for TV, to ensure reasoned and defensible methodology in patient care. We also include a tracheostomy counselling info kit applicable for use prior to tracheostomy insertion.