The recent decision of the court of appeal in the case of Arbili v Arbili has highlighted once again the difficulties encountered by a divorcing party who attempts to obtain documents from a reticent spouse.

It can often be tempting for one spouse, suspicious that the other has not been upfront as to the true extent of his or her assets, to seek to uncover the truth through underhand, and even illegal, means. Examples of such behaviour highlighted in case law include hacking into email accounts, raiding filing cabinets, opening letters addressed to the other party and copying documents left in unlocked offices. Often the aggrieved spouse does these things personally; however, sometimes an enquiry agent will be employed.

In the case of Arbili v Arbili the husband attempted to set aside a financial order on divorce by relying upon information that his private investigator had illegally obtained from the wife's computer account. He claimed that the documents demonstrated that the wife had not made full disclosure to the court.

Having obtained the documents illegally, the husband then complied with his legal obligation and immediately returned them to his wife, without retaining any copies. Following a statement submitted by the wife dealing with the contents of those documents, the court effectively dismissed the husband's application, ruling that he had failed to clarify what he alleged he had seen in the documents that contradicted his wife's statement. The court was critical of the manner in which the documents had been obtained, the intrusion into his wife's private life and the resulting delay and additional costs. All of the husband's investigations had come to nothing.

This is a common problem faced by many going through a divorce, mistrustful of their spouse and suspicious that assets will be hidden and squirrelled away. However, the modern view is that courts cannot be seen to encourage either party to obtain documents by illegal means. It is easy to be critical of the law in its attempt to balance the competing interests of two aggrieved spouses; one hampered by the other's lack of frank disclosure, and the other seeking to rely on civil and criminal law to uphold his or her right to privacy.

Over time, the divorce courts in England and Wales have firmly followed the criminal and civil law, with the result that the enquiring spouse is likely to get into hot water, to no avail. Breaching privacy laws, whether by personal sleuthing or by use of an enquiry agent, merely brings down the might of the court against the sleuth rather than their possibly non-disclosing spouse. It is simply unlawful for a spouse to copy documents belonging to the other - whether hard copies or electronic - without permission. The fact that the parties are married does not justify behaviour that would otherwise be unlawful. If a spouse illegally obtains confidential information, the injured spouse is entitled to relief such as an injunction or an order that the documents be returned and all copies destroyed. Penalties include civil and criminal sanctions, theft or burglary charges, costs orders and charges under the Computer Misuse Act or the Data Protection Act. The resultant damage to that party's credibility may be significant within the divorce proceedings, resulting in orders to pay the other's costs, which can be crippling.

For the unfortunate solicitor who is handed a pile of dubiously obtained documents, the position is particularly tricky. The obligation is immediately to send the documents on to one's opponent, making it clear that no copies have been retained. This is what Mr Arbili did in the case in hand. It is then left to the opponent to disclose the relevant information, and all that the shamed enquirer can do is rely on the knowledge gained from those documents in order to challenge the accuracy of the disclosure, although doing so may risk civil or criminal proceedings.

These developments have inevitably had a knock-on effect on the role of private investigators, who formerly enjoyed lucrative employment for aggrieved spouses seeking to uncover illicit financial dealings, secret families and hidden foreign accounts. Private investigators, as husband and wife alike, are not permitted to obtain confidential information, for example, by hacking into computer accounts or breaking into offices. Any spouse seeking to rely on such information may face the court sanctions set out above.

Nowadays, therefore, the use of private investigators in divorce proceedings is not generally recommended save in exceptional circumstances, and their work must be strictly limited to lawful means. One continuing assignment is to find out whether a spouse is having an affair, which can then be cited in the divorce petition. In England and Wales, however, the reasons for the breakdown of a marriage are essentially disregarded by the courts in respect of the division of the finances.

However, finding out about a new relationship, particularly when it involves cohabitation with a new partner, can have significant financial implications, as it can be argued that the needs of the newly cohabiting spouse are reduced through shared housing and outgoings.

Another useful job is carrying out an in-depth analysis of a spouse's bank statements in order to uncover any dubious transactions pointing to the existence of undisclosed accounts; however, such work is often simply carried out by solicitors experienced in dealing with such cases, or alternatively forensic accountants employed for that very purpose.

The crucial point for any mistrustful spouse seeking to proceed in this way will be to ensure that the private detective will operate within the law in this constantly developing field. Any documents or information must be lawfully obtained with regard to the opposing spouse's right to privacy. The risks of stepping over the line are significant.

In the absence of 'self help' methods or the employment of private investigators, and where the level of assets justify it, there are more conventional ways to find hidden information through recourse to the family courts. An example is 'search and seize' orders in respect of documents and/or electronic data, whether in the home or in the office. Freezing orders are another remedy, used to freeze assets until the resolution of the proceedings. Orders may also be made against third parties, such as accountants or business partners, requiring them to provide documents. The problem with these methods, however, is there is a high burden of proof on the person seeking the production of such documents. A discrete application can be prohibitively expensive. A more practical solution, therefore, is to focus on the court's ability to draw adverse inferences from non-disclosure.

For the majority of divorcing couples, disclosure will be provided voluntarily through the court's procedures, and any gaps in disclosure will be apparent from a detailed analysis by solicitors or forensic accountants of the documents provided. For the few in the unfortunate position of being unable to prove that undisclosed assets exist, the law now makes it very difficult simply to help oneself. Parties must tread carefully to ensure their actions do not stray into illegal territory.

It can often be tempting for one spouse to seek to uncover the truth through underhand, and even illegal, means.

The divorce courts in England and Wales have followed the criminal and civil law, which means that the enquiring spouse is likely to get into hot water.

A more practical solution is to focus on the court's ability to draw adverse inferences from non-disclosure.

This article was written by Barbara Simpson and Harriet Errington from the family team and first appeared in the Financial Adviser in June 2015.