A VERDICT in the shareholder action against Royal Bank of Scotland is unlikely to emerge until 2017 or 2018 - a decade after the controversial rights issue at the centre of the claim.Action groups suing the bank for billions of pounds in damages do not expect the case to come to the High Court until at least 2016 and some fear that there will be more delays.Four separate groups allege RBS misled investors about its financial strength at the time of its GBP12 billion rights issue following its disastrous acquisition of a major part of ABN Amro bank the previous year.There have already been a number of case management hearings in the London High Court before Justice Hildyard to decide how the trial will be conducted, with a further one due next month after an earlier cancellation.A legal source close to one of the RBS shareholder action groups said: "We believe the July meeting will decide whether the eventual trial is to be split between separate hearings for liability and quantum [the amount of any damages and costs awarded]."What with the summer break, that would probably mean the key hearing to decide the timing of the case will not be before this autumn. And our estimate is that this would mean the case not being heard before 2016, a full eight years after the rights issue."And then it is difficult to know how long the case will go on. It is a very big case, with lots of expert witnesses on both sides. In addition, the courts are very busy anyway."Another source said: "The cut-off date for when new shareholders can join the various actions is gone. Nobody else is going to be joining. But it is frustrating that so many years have passed before investors can possibly get any redress for what they feel has been misleading behaviour by RBS. And many of them are elderly so the time that elapses is a highly relevant factor."The RBoS Shareholders Action Group, representing 100 institutional investors and about 12,000 private shareholders, has launched a GBP4bn legal action against the bank and four former directors.They are former chief executive Fred Goodwin, chairman Sir Tom McKillop, investment banking boss Johnny Cameron and finance director Guy Whittaker.A separate claim valued at about GBP20 million has been launched by the RBS Rights Issue Action Group on behalf of 3,500 small shareholders.Law firm Stewarts Law, representing more than 300 institutional shareholders, has a claim estimated to be worth about GBP1bn.And corporate litigation firm Quinn Emanuel is representing five major institutional investors who are pursuing their own separate action against RBS: Edinburgh-based Standard Life Investments; Legal & General Investment Management; Prudential; Aviva; and the University Superannuation Fund.RBS says it will vigorously defend the claims. The bank has already disclosed that its estimated costs for the much-delayed legal action will be approximately GBP42m.A key victory for the thousands of small shareholders came when the judge ruled late last year that if costs were awarded against the plaintiffs they would be capped on how many shares institutional and private investors took up in the stock market cash call.The rights issue came months before RBS crashed to a record GBP24bn loss and into majority taxpayer ownership.In 2012 US courts found in the bank's favour regarding two legal actions related to the cash call by holders of RBS preference shares and American depositary receipts.