Authored By: Brian Naheso
Introduction
‘A sensible society is one where human beings learn from the mistakes of the past and are indeed guided by the most enlightened never to repeat the same faux pas again.’1 Law sometimes applies retroactively, which may cause constitutional problems whenever it affects individuals’ rights, since retroactivity runs contrary to a foundational function of the liberal constitution: the principle of legal certainty. Legal certainty is considered important to the rule of law, as citizens who perceive the law as fair and comprehensible may be more likely to follow it. However, the law serves the vigilant, not those who sleep.2
Legal Certainty
The principle of legal certainty is becoming increasingly prominent as a legal tool to address uncertainty in the legal order.3 It is a requirement of accessibility and predictability of the law, so that those affected by it can reasonably anticipate the consequences of their actions.4 It is the principle of proper law-making,5 and it is what defines a legal system. Fuller defines a legal system on the basis of eight principles that reflect some key requirements of the principle of certainty of law.6 His principles concern the generality of laws, the demand that laws be published, that they be non-retroactive, clear, and consistent, that they do not impose duties impossible to perform or be modified too frequently, and that governmental action be in accordance with general laws laid down beforehand.7
All of what is called positive law stems from the requirement of legal certainty.8 Legal certainty is thus grounded in positivity. Positivism is based on the perception that an appropriate description of law requires separation from moral judgments — for instance, in relation to the value of the present law, or with respect to the manner in which law should be amended or developed.9
The struggle between legal certainty and equity, however, is as old as the law itself.10 On one side lies the public interest in clear, equal, and foreseeable rules of law that enable those subject to them to order their behaviour so as to avoid legal conflict or to make clear predictions of their chances in litigation.11 On the other lies the need to decide current, concrete disputes adequately, by giving due weight to the special and perhaps unique circumstances of each case.12 The former calls for legislation; the latter, for judicial decision.13
There exists a tension between having a general rule universally and equally applicable to all cases at all times, and the effort to reach what may appear to be the most just outcome between the parties on the particular facts of each case.14 A balance must be achieved between the two. Laws are important, but they should not be so rigid and fixed as to make change difficult or impossible — a condition that would constitute a clog upon national development or an incentive to revolutionary reform.15
The Constitution of Kenya, 2010, and the Rule Against Retrospectivity
Why are constitutions seen as fundamentally important?16 The whole point of a constitution is to organise politics and society in particular ways.17 It may well be that we begin wanting a constitution, only to find that achieving a good one is no simple task.18 Good constitutions anchor certain tenets that have garnered recognition as hallmarks of democratic dispensation — among them, the doctrine of the rule of law.
The Constitution is the supreme law of the land and the supreme source of all other laws. All other laws derive their legitimacy from it and must accord with it; otherwise they are null and void. It was made by Kenyans directly and as such represents their will.19 The mandatory character of compliance with the Constitution — its supremacy over all individual citizens, legal entities, state authorities, and institutions — ensures the order and hierarchy of the legislative framework as a manifestation of the will of the state.20
In the realm of criminal matters, the Constitution rightly provides for the rights of individuals, including those of accused persons. Article 50(2)(n) requires the clear establishment of both an offence and its punishment before a finding of guilt can be made. No person is guilty of an offence that was not in truth committed, or that was not an offence known to the law at the relevant time.
With regard to the general rule against retrospective application of the law, the Supreme Court in Samuel Kamau Macharia & another v Kenya Commercial Bank Limited & 2 others [2012] eKLR held that a Constitution is not necessarily subject to the same principles against retroactivity as ordinary legislation, as it looks forward and backward, vertically and horizontally, seeking to re-engineer the social order in quest of its legitimate object of rendering political goods. In this way, a constitution may and does embody retrospective provisions or provisions with retrospective ingredients.21
The Supreme Court, however, warned that a court of law must pay careful attention to the language used in the Constitution. If the words used in a particular provision are forward-looking, and do not contain even a trace of retrospectivity, the court ought not to import it into the language of the Constitution. The Supreme Court further noted that where a retrospective application would have the effect of divesting an individual of rights legitimately acquired before the commencement of the Constitution, care should be exercised.
The upshot is that, for the court, the primary language of the Constitution should always serve as the starting point for any inquiry into its meaning.22 To properly understand and interpret a statute, one must read the text closely, keeping in mind that the initial understanding of the text may not be the only plausible interpretation, or even the correct one.23
Law therefore plays an important indirect role in social change by shaping a direct impact on society.24 Ignorance of the law may be no excuse, but too much knowledge of the law is apparently no virtue. Knowledge of and advice about the law is, however, undeniably desirable in most circumstances.25
Both legislation and decisions by courts in the long run will enhance public awareness. If some individuals can violate a norm without incurring any risk, its observance cannot reasonably be expected of anyone.26 The threat of sanction can deter people from violating the law, in part by inducing a moralistic attitude toward compliance.27 This leads to the necessity of the connection between law and coercion as a decisive element of social efficacy.28 Legal awareness essentially fosters social development.29 Courts will, however, be required to balance the interests of society with those of individuals and groups.30
Conclusion
The principle of legal certainty is not merely a theoretical aspiration; it is an indispensable pillar of the rule of law and a practical requirement for the functioning of a just society. In Kenya, the Constitution of 2010 provides the framework within which this principle operates, setting limits on retroactivity, demanding clarity of offences and punishments, and conferring upon courts the responsibility of interpreting the law in a manner faithful to its text and purpose. The tension between certainty and equity will never be fully resolved, but it must be carefully and continuously navigated through principled adjudication and sound legislation. As the Supreme Court recognised in Samuel Kamau Macharia, even a Constitution must be read with precision — its language is the beginning, not the end, of the inquiry.
‘The law is not a light for you or any man to see by; the law is not an instrument of justice; the law is a causeway upon which, so long as he keeps to it, a citizen may walk safely.’ — Robert Bolt
Bibliography
Case Law
R v Oakes [1986] 1 SCR 103
Samuel Kamau Macharia & another v Kenya Commercial Bank Limited & 2 others [2012] eKLR
Books
Alexy, R., ‘A Defence of Radbruch’s Formula,’ in Freeman, M. D. A. (ed.), Lloyd’s Introduction to Jurisprudence (8th edn, Sweet & Maxwell, 2008) pp. 426–443
Brian Bix, Jurisprudence: Theory and Context (5th edn, Sweet & Maxwell, 2009)
Christopher G. Wren and Jill Robinson Wren, The Legal Research Manual: A Game Plan for Legal Research and Analysis (2nd edn, 1986)
Gavison, R., ‘What Belongs in a Constitution?’ Constitutional Political Economy 13(1) (2002)
Gregor, M. (ed. and trans.), Immanuel Kant: The Metaphysics of Morals (Cambridge University Press, 1996)
Hardin, R., ‘Why a Constitution,’ in The Social and Political Foundations of Constitutions (2013)
Freeman, M. D. A. (ed.), Lloyd’s Introduction to Jurisprudence (2014)
William N. Eskridge et al., Cases and Materials on Legislation: Statutes and the Creation of Public Policy (3rd edn, 2001)
Journal Articles
Alexy, Robert, ‘Legal Certainty and Correctness,’ Ratio Juris 28(4) (2015)
Bartholomew, P. C., ‘The Morality of Law by Lon L. Fuller,’ (1964) 58 American Political Science Review 984; see also Tucker, Edwin W., ‘The Morality of Law, by Lon L. Fuller,’ Indiana Law Journal, Vol. 40, Issue 2, Article 5
Coudert, Frederic R., ‘Certainty and Justice,’ The Yale Law Journal, Vol. 14, No. 7 (1905)
Maxamat, N. O. and Burxoniddin, K. F., ‘Legal Education Is the Basis for the Development of Society,’ Journal of Ethics and Diversity in International Communication, 2(2) (2022)
Paul Heinrich, ‘Legal Certainty versus Equity in the Conflict of Laws,’ Law and Contemporary Problems, Vol. 28, No. 4 (1963)
Popelier, P., ‘Legal Certainty and Principles of Proper Law Making,’ European Journal of Law Reform, 2 (2000)
Popelier, P., ‘Five Paradoxes on Legal Certainty and the Lawmaker,’ Legisprudence, 2(1) (2008)
Schwartz, Richard D. and Orleans, Sonya, ‘On Legal Sanctions,’ The University of Chicago Law Review, Vol. 34, No. 2 (1967)
Stoian, Alexandru and Drăghici, Teodora, ‘The Principle of Legality, Principle of Public Law,’ International Conference Knowledge-Based Organization (2015)
Stephen McG. Bundy and Einer Elhauge, ‘Knowledge about Legal Sanctions,’ Michigan Law Review, Vol. 92, No. 2 (1993)
Online Materials
Kishan Tiwari, ‘Importance of Law in Society,’ Legal Desire
Law For All — Vigilantibus Non Dormientibus Jura Subveniunt
Footnote(S):
1 Dennis Mukoya, ‘Judicial Activism: The Impediment to Tangible Civic Reform in Kenya: The Tyranny of the Bench,’ available at dennismukoya.wordpress.com (accessed 31 January 2026).
2 lawforall.in/vigilant/ (accessed 31 January 2026).
3 Popelier, P., ‘Five Paradoxes on Legal Certainty and the Lawmaker,’ (2008) Legisprudence 2(1), pp. 47–66. Available at doi.org/10.1080/17521467.2008.11424673 (accessed 31 January 2026).
4 Ibid.
5 Popelier, P., ‘Legal Certainty and Principles of Proper Law Making,’ (2000) European Journal of Law Reform 2, p. 321.
6 Bartholomew, P. C., ‘The Morality of Law by Lon L. Fuller,’ (1964) 58 American Political Science Review 984; see also Tucker, Edwin W., ‘The Morality of Law, by Lon L. Fuller,’ Indiana Law Journal, Vol. 40, Issue 2, Article 5, available at repository.law.indiana.edu/ilj/vol40/iss2/5 (accessed 31 January 2026).
7 Ibid, Tucker.
8 Gregor, M. (ed. and trans.), Immanuel Kant: The Metaphysics of Morals (Cambridge University Press, 1996).
9 Brian Bix, Jurisprudence: Theory and Context (5th edn, 2009) p. 33.
10 Paul Heinrich, ‘Legal Certainty versus Equity in the Conflict of Laws,’ Law and Contemporary Problems, Vol. 28, No. 4 (1963), pp. 795–807. Available at doi.org/10.2307/1190565 (accessed 31 January 2026).
11 Ibid.
12 Ibid.
13 Ibid.
14 Coudert, Frederic R., ‘Certainty and Justice,’ The Yale Law Journal, Vol. 14, No. 7 (1905), pp. 361–73. Available at doi.org/10.2307/781604 (accessed 31 January 2026).
15 Ibid, p. 362.
16 Hardin, R., ‘Why a Constitution,’ in The Social and Political Foundations of Constitutions (2013), p. 51.
17 Ibid, p. 52.
18 Gavison, R., ‘What Belongs in a Constitution?’ Constitutional Political Economy 13(1) (2002), pp. 89–105.
19 Constitution of Kenya, Art. 1.
20 Stoian, Alexandru and Drăghici, Teodora, ‘The Principle of Legality, Principle of Public Law,’ International Conference Knowledge-Based Organization (2015).
21 Samuel Kamau Macharia & another v Kenya Commercial Bank Limited & 2 others [2012] eKLR, at paragraph 62.
22 See Eskridge, William N. et al., Cases and Materials on Legislation: Statutes and the Creation of Public Policy (3rd edn, 2001) p. 819.
23 Christopher G. Wren and Jill Robinson Wren, The Legal Research Manual: A Game Plan for Legal Research and Analysis (2nd edn, 1986).
24 Kishan Tiwari, ‘Importance of Law in Society,’ available at legaldesire.com (accessed 31 January 2026).
25 Bundy, Stephen McG. and Elhauge, Einer, ‘Knowledge about Legal Sanctions,’ Michigan Law Review, Vol. 92, No. 2 (1993), pp. 261–335. Available at doi.org/10.2307/1289667 (accessed 31 January 2026).
26 Alexy, Robert, ‘Legal Certainty and Correctness,’ Ratio Juris 28(4) (2015), pp. 441–451.
27 Schwartz, Richard D. and Orleans, Sonya, ‘On Legal Sanctions,’ The University of Chicago Law Review, Vol. 34, No. 2 (1967), pp. 274–300. Available at doi.org/10.2307/1598934 (accessed 31 January 2026).
28 Alexy, R., ‘A Defence of Radbruch’s Formula,’ in Freeman, M. D. A. (ed.), Lloyd’s Introduction to Jurisprudence (8th edn, 2008) pp. 426–443.
29 Maxamat, N. O. and Burxoniddin, K. F., ‘Legal Education Is the Basis for the Development of Society,’ Journal of Ethics and Diversity in International Communication, 2(2) (2022) pp. 5–8.
30 R v Oakes [1986] 1 SCR 103, paras 69–70.
