Next month the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) will be published, having been approved at the end of last year by the Board of Trustees of the American Psychiatric Association.

There are two major psychiatric classification systems for illnesses: the International Classification of Diseases or ICD (currently version 10, with an 11th edition due in 2015) and the Diagnostic and Statistical Manual of Mental Disorders. Whilst the ICD system is more generally used in the UK and Europe, and the DSM system more common in the United States and Canada, some UK psychiatrists prefer the DSM classification system.

The classification of psychiatric conditions has always been controversial. Many criticise the increasing trend towards classification of symptoms because such approach, from a treating perspective, focuses on individual symptoms rather than the full picture and the cause thereof.

The new DSM-5 has been particularly criticised by psychiatrists and psychologists. Some are concerned that the new edition reclassifies as mental illness “normal human experiences”. For example, the new DSM edition widens the diagnostic criteria for grief reactions so that symptoms which might previously have escaped classification – being considered instead as a “normal” human experience – may now be relabeled as a clinical disorder.

Psychiatrist Professor Allen Frances (and chair of DSM-IV) has been particularly vocal in her criticism of proposed revisions to the DSM-5. She has warned that the new DSM-5 risks “medicalising normality”. She has given examples of new psychiatric classifications which incorporate behaviour which may not have been labeled as an illness previously. These include: “Disruptive Mood Dysregulation Disorder” for temper tantrums; Major Depressive Disorder which now includes normal grief; “Generalized Anxiety Disorder” which includes everyday worries.

The new classification system for psychiatric illness has the potential to increase the numbers of people eligible to bring a compensation claim for psychiatric injury where there has been no physical injury.

In order to recover compensation for adverse psychological symptoms in such circumstances, there has to be a diagnosis of a “recognised psychiatric condition”. In the case of Honz v Berry Lord Denning held that whilst damages would not be awarded for grief or sorrow, damages will be awarded “for nervous shock or, to put it in medical terms, for any recognisable psychiatric injury caused by breach of duty by the defendant”.

Whilst the criterion of “recognised psychiatric condition” has been subsequently followed, there has been much debate as to its actual meaning.

The case was heard in 1970 and the comments, in particular the criterion of “recognisable psychiatric injury”, were made prior to the huge increase in diagnostic categories. For example it is clear that a grief reaction can now be formally diagnosed as a mental illness.

The starting point is usually accepted to be a formal classification under either the ICD or DSM classification systems. However, the fact that a claimant’s symptoms fit within one of the classification brackets does not automatically mean that the court will accept the diagnosis from a legal perspective – the courts are not bound to follow the medical profession in this regard. The editors of the DSM-IV specifically stated that there is an “imperfect fit between the questions of ultimate concern to the law and the information contained in the clinical diagnosis”.

The growing discord in the medical profession regarding the classification of psychiatric illness has the potential at least to reopen the debate as to the categories of people who are eligible to claim compensation for psychiatric illness where someone else is to blame.

For the time being however, as the psychiatric profession continues the trend towards the increasing classification of symptoms, more conditions may fall within the definition of psychiatric injury and more claimants can potentially recover compensation where they have had an adverse reaction to a shocking event.