In a landmark case the 43 cancer victims are suing Imperial Tobacco and Gallaher for negligence in not warning customers about the risk of the lung cancer and failing to reduce the level of tar in cigarettes when they discovered links between smoking and the disease.
Denied legal aid, the victims have been forced to employ law firms on a no-win, no-fee basis. However, Gallaher and Imperial are maintaining that the solicitors should be liable for the tobacco industry's legal costs as well as their clients' if the action eventually fails.
This could saddle the solicitors with a bill of as much as pounds 20m, a risk they are unlikely to accept. If they are forced to pull out of the case then the 43 litigants would have little choice but to call off the action. Not only that, the ruling would set a precedent which could scupper any future claims.
However if the victims are successful in quashing the tobacco company's case it would remove the last major obstacle in the legal action, which is due to go to court next year. Such an action could turn out to be hugely costly for Imperial and Gallaher and force the companies to submit thousands of potentially damaging documents to the court.
More importantly it could open the floodgates, prompting a huge number of lung cancer victims to pursue their own cases, which could have devastating consequences for the industry. The situation in the US, where threat of escalating legal action has forced tobacco companies into a deal that could cost them hundreds of billions of dollars, could be mirrored in the UK.
Clive Bates, director of Ash, the anti-smoking lobby group, said: "If the tobacco industry wins, all further prospects for litigation in the UK look doomed, at least for the foreseeable future. If the victims win, the legal cases will start gathering momentum. The law is only now waking up to the fact that these companies are responsible for killing half their customers and 120,000 people a year in the UK."