Most people would agree that the role of law is to achieve justice, however justice is a term which can only be defined subjectively; it relates to an individual’s moral standpoints. A utilitarian may argue that justice is served when the greatest good is done for the greatest number, whereas a Marxist may assert that justice is done only when all is equal in terms of wealth distribution. Justice may be easier to define holistically if its antonym ‘injustice’, in meaning that which is unfair, is appreciated. It is useful to categorise justice into ‘substantive justice’ and ‘formal justice’ when attempting to comprehend its nature.

Substantive justice pertains to the need of law itself to be just, whether created through legislature or legal precedent. What is considered just may vary from person to person, yet the prevailing moral leaning of society will often dictate whether a law is seen as just

Formal justice is concerned with ensuring that legal principles are applied in a fair way. This means there must be a following of legal rules; all like cases should be treated alike and, conversely, unalike cases should be treated unalike. A lack of bias is essential when a judge is hearing a case, and procedure must be applied evenly and equally to all.

Substantive justice and formal justice differ in that formal justice’s jurisdiction lies in the procedural domain of following rules, whereas substantive justice seeks to ensure that the rules themselves are fair. Formal justice is concerned with treating like cases alike, and substantive justice must specify what counts as alike. Formal justice is easier to apply rigidly if one asserts that all laws, whether fair or not, if applied equally to everyone, are therefore just. Substantive justice, on the other hand, has the complex task of ascertaining exactly what is fair.

There can be conflicts of justice when the two try to operate side by side. Before 1991, there was no offence of rape within marriage. The case of R V R [1991], which created the offence, showed considerable substantive justice for society as a whole, however formal justice may not have prevailed. I recently read a blog postwhose address I fail to recall, which commented on an aspect of the works of A.V. Dicey, which pertained to legal procedure, saying that “in principle no law should have retrospective effect”.

We expect law to be fair and just in its principles and in the way that they are applied. We do not just expect substantive justice, or formal justice; we expect something entirely more complex and incredibly difficult to achieve: a synergy of the two.