Preliminary forecasts indicated a decision would be made in the first half of the year, but it appears increasingly likely that it will not be forthcoming before the autumn.

The Permanent Court of Arbitration, which acts as a secretariat of sorts for the ad hoc arbitral tribunal set up under an intergovernmental agreement, is tight-lipped about the release date given that the procedure is confidential. The Slovenian and Croatian foreign ministries say they have no indication when the ruling might be issued.

Unless the two sides agree to a public presentation, the ruling will be published on the website of the Permanent Court of Arbitration. Slovenia would not mind a public declaration, but Simona Drenik, one of Slovenia's agents in the procedure, told the STA the two sides would first have to consent to that.

According to the 2009 arbitration agreement, the arbiters are under no time constraints. The accord merely stipulates that the tribunal will decide "expeditiously after due consideration of all relevant facts pertinent to the case".

But the expectation is that the proceedings should not take much longer given that it has been over three years since the tribunal held its first session, on 13 April 2012, and over five years since the arbitration treaty was signed.

During this period Slovenia and Croatia have gone through painful ratification procedures, which at one point jeopardised Croatia's EU accession, selection of arbiters, preparation of memorandums and, finally, the oral arguments.

The most contentious bit of the agreement, and probably the most difficult issue for the arbiters as well, is the determination of the maritime border, or what the agreement described as Slovenia's "junction" to the high seas.

In Slovenia's reading of the agreement, "junction" means "contact of territorial waters with international waters" and hence open access to the high seas.

Croatia, on the other hand, sees it as merely a link to the high seas via its territorial waters, an arrangement giving Slovenia "physical contact" with the high seas.

This view rests on Croatia's argument that the maritime border should run through the middle of Piran Bay towards the maritime border with Italy, which would render Slovenia's direct access to the high seas impossible.

Slovenia, however, has been warning that the arbitration would be considered not to have done its job if it merely grants Slovenia "harmless passage" through Croatian waters.

Despite the political debates focusing on the maritime border, the tribunal will determine the course of the entire border, all 670 kilometres of it, Slovenia's junction to the high seas, and the regime for the use of the relevant maritime areas.

But even that point is moot, as evident from the tribunal's summary of the oral arguments.

Croatia reasoned the three points determine the order of precedence for the tribunal, which it says must first determine the border, then the junction and subsequently the maritime regime.

Slovenia, on the other hand, argued that the three points constitute a single and indivisible task for the arbiters.

Both countries expect that the arbiters' decision will be a definitive resolution of the long-standing open issues not causing new frictions - that their decision is precise, leaving little scope for disagreement.

If the delineation of the border is looser, both sides may request additional explanations, but their work will have been completed: any new disagreements as to the interpretations will have to be resolved bilaterally or, once again, in court.

After the verdict is announced both sides will have six months to "implement the award, including by revising national legislation, as necessary", according to the agreement.

According to Drenik, the six-month term refers primarily to the respective country exerting full jurisdiction over the portions of the disputed territory they will be awarded.

It does not apply to the full alignment of all documents, including legal records, a process that could take much longer.