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Duty-based theories: the principles of biomedical ethics

Peter Ellis - Independent Nursing, Health and Social Care Consultant, Writer and Educator Hannah Ellis - Senior Paralegal Coordinator First published:

There are various ethical theories and approaches which nurses can use to guide their practice. This article examines the ethical approach associated with duty-based ethics (or deontology). Duty-based ethical theories cover the distinction between actions that are ‘right’ and ‘wrong’. Unlike other ethical theories, such as consequentialism, duty-based ethics are not concerned with the outcome of an action. This article explores the most prominent duty-based theory of biomedical ethics put forward by Beauchamp and Childress (2019).

Duty-based ethics

Duty is a key feature in many religions, especially the Abrahamic religions (Judaism, Christianity and Islam), and is engrained in the ethical traditions of the UK. For example, Christianity defines people’s basic duties in the ten commandments, which outline what people may and may not do (eg you shall not steal, you shall not commit murder).

Such traditions have informed western philosophy and ethical thought for hundreds of years, perhaps most famously in the work of Immanuel Kant (1724–1804). His categorical imperative ‘Act only according to that maxim whereby you can at the same time will that it should become a universal law’ (Kant, 1991) is widely cited. Kant’s categorical imperative posits that people should follow a duty in all situations, regardless of the consequences. For example, if someone should not lie in one situation, then they have a duty to never lie in any circumstances. However, duty-based theories have become more lenient over the years, allowing consideration of extreme circumstances (eg lying to protect victims of persecution).

The four-principles approach

Beauchamp and Childress have been the leading proponents of ethics in healthcare since the 1980s and introduced the concept of the four-principles approach.

While the four principles do not represent the full picture of duty-based ethics, it is important that nurses understand this to engage in ethical thinking, debate and activity.

The four principles of biomedical ethics are, according to Beauchamp and Childress (2019), the duty to consider:


Beneficence simply means doing good; it is about taking an action as opposed to avoiding harm by doing nothing. Bester (2020) defined beneficence as the foundational ethical principle of medicine, which advocates promoting and protecting the wellbeing and interests of patients.

Beneficence is difficult to define, as there are different views about what is considered best for a person’s wellbeing and their interests. Broadly speaking, patient needs, in terms of wellbeing and benefit, can either be objective (ie a benefit from a medical or nursing perspective) or subjective (benefits in a contextual sense, such as preserving a patient’s dignity) (Ellis, 2020).

Avant and Swetz (2020) observed that patients usually want treatments that prolong their lives or improve their functionality. In this sense, beneficence can be considered the duty to do good, as defined by both the patient and care staff.


Non-maleficence refers to not doing harm, essentially requiring nurses to provide care for people without causing them harm. Similar to beneficence, it is difficult to provide an all-encompassing definition of this ethical principle. For example, one might reasonably consider harm to be the unnecessary infliction of pain, while others may be more literal and consider all pain to be harmful.

The main difference between non-maleficence and beneficence is that the former advocates avoiding harm, while the latter involves actively promoting a person’s wellbeing. For example, non-maleficence may involve not causing someone harm by not hitting them, while beneficence arises from helping someone who is in danger.

Non-maleficence is, therefore, not about avoiding all harm, but about the duty to avoid inflicting unnecessary or deliberate harm (Barker, 2017).


For many, the duty to observe, protect and promote the autonomy of others is the most important duty-based principle of biomedical ethics (Taylor, 2018). The word ‘autonomous’ derives from the Greek ‘auto’ (self) and ‘nomos’ (law). This principle suggests that nurses should regard people as having an intrinsic worth, so patients must be allowed to make choices about their own lives according to their capacity for self-determination (Varkey, 2021).

Asking for consent is a fundamental way in which nurses can demonstrate their respect for the autonomy of an individual, as this provides individuals with the self-determination to make choices about what happens to their bodies.

Autonomy is a central feature of the Mental Capacity Act 2005, which additionally requires the individual exercising it to have capacity. Within the act, people who are deemed to have capacity (everyone unless proven otherwise) have the right to make autonomous decisions about their own lives, including decisions which may be considered ‘wrong’ by others.


Justice is a form of fairness. Ethically, fairness means treating people equally at all times and, in the UK, reflects the requirements of the Equality Act 2010, in which people should be treated equally and not discriminated against based on certain protected characteristics (eg age, disability, religion, sexual orientation).

Justice requires that nurses behave the same way towards and with different people in similar situations. For example, nurses might always tell patients the truth about their health condition regardless of any other considerations, because this is usually beneficent to the patient and promotes equal treatment.

In some situations, nurses may be required to act as advocates for patients who otherwise would not receive fair treatment (Abbasinia et al, 2020). Justice may also relate to the way nurses allocate their time and resources to supporting the wellbeing of patients, where more time and resources may be allocated to sicker patients, because this is considered the fair thing to do (Yeo et al, 2020).

The scope of the four principles

While each of the four principles of biomedical ethics are important, one principle may take priority over another in certain situations. Therefore, nurses considering duty-based approaches to ethical decision making will need to exercise scope (Beauchamp and Childress, 2019).

Scope requires some discretion and consideration of the nature of the situation in which nurses find themselves, enabling them to consider which duty is the most important in a given situation. For example, a nurse cannot always enable someone with advanced dementia to act autonomously, as they may put themselves in danger, but the nurse can still ensure that the person does not come to any harm and do the same for all people in similar situations.

Other duties

There are a number of other duties which apply to nursing practice, including:

These duties are specific to certain situations and behaviours and, as such, are applied without scope.


Any situation may require the nurse to consider more than one approach to ethical decision making and take into consideration other ethical theories and topics, such as consequentialism or human rights. However, duty-based ethics form a critical foundation of the way in which ethics operate in healthcare, providing nurses with ethical guidance that may enable them to be more confident and competent in their practice.

Reflective exercise

Consider the following case:

You are caring for Amina, a 78-year-old widow, who has been admitted to hospital following a collapse at home. Amina has been found to have a very advanced aggressive lung cancer which is not treatable. The doctors estimate that Amina has 3–6 months left to live. Amina does not understand English and her daughter, who has acted as her translator, is refusing to tell Amina her prognosis because she may become upset.

Considering each of the four principles of biomedical ethics, consider what they might require from you when managing this situation:

  • beneficence
  • non-maleficence
  • autonomy
  • justice

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Avant LC, Swetz KM. Revisiting beneficence: what is a ‘benefit’, and by what criteria? Am J Bioethics. 2020;20(3):75-77. https://doi.org/10.1080/15265161.2020.1714808

Barker P. Ethical dilemmas in palliative care. InnovAiT. 2017;10(8):489-492. https://doi.org/10.1177/1755738017712536

Beauchamp T, Childress J. Principles of biomedical ethics. 8th edn. Oxford: Oxford University Press; 2019

Bester JC. Beneficence, interests, and wellbeing in medicine: what it means to provide benefit to patients. Am J Bioethics. 2020;20(3):53-62. https://doi.org/10.1080/15265161.2020.1714793

Ellis P. Understanding ethics for nursing students. 3rd edn. London: Sage; 2020

Kant I. The metaphysics of morals. Cambridge: Cambridge University Press; 1991

Taylor JS. Introduction: autonomy in healthcare. Health Care Ethics Committee Forum. 2018;30:187–189. https://doi.org/10.1007/s10730-018-9360-9

Varkey B. Principles of clinical ethics and their application to practice. Med Princ Pract. 2021;30(1):17–28. https://doi.org/10.1159/000509119

Yeo M, Moorhouse A, Khan P, Rodney P. Concepts and cases in nursing ethics. 4th edn. Ontario: Broadview Press; 2020

Peter Ellis

Hannah Ellis