When the World Trade Center was attacked by terrorists on 11 September 2001, the world seemed to stop turning. Such was the magnitude of the disaster and the sheer horror of what had happened, much of the world was shocked into a disbelieving inertia.

Recovery strategy: Freehills' Michael Mills and Michelle Fox played key roles in resolving one of the largest US mass tort litigation cases

But for the thousands of brave people who rushed to the aid of survivors and later assisted with the clean-up and reconstruction effort, life has delivered much more than a sense of dread and abhorrence about that fateful day.

Following the collapse of the twin towers, around 90,000 people assisted in the rescue effort and the massive clean-up which followed. Of those 90,000, many were employees of contractors, such as Bovis Lend Lease, which had responded to the New York Mayor's call to action.

In the years that followed, more than 10,000 people involved in the first response and clean-up claimed to have been injured or have fallen ill, most as a direct result of exposure to toxic substances.

Many workers claimed that their employers had not provided appropriate equipment or supervision as they worked amongst the ruins.

However, under previously existing laws, injured workers could only seek recovery for their injuries by suing the contractors and the City of New York and as such, class actions seeking over $10 billion in compensation were commenced in 2003.

Freehills lawyers Michael Mills and Michelle Fox, acting for Bovis Lend Lease (Bovis), worked in conjunction with US firm Weil, Gotshal & Manges to reach a settlement for the 10,000 plaintiffs, as well as 8,000 plaintiffs who made spousal claims.

This was achieved through a legislative strategy that sought to avoid large-scale litigation, which was seen by many as the pitting of "heroes against heroes", and provide a fair settlement for plaintiffs.

"There was a fair bit of emphasis [on] finding resolution strategies for such a massive piece of litigation, with 18,000 plaintiffs running through court," said Mills.

"As the judge correctly said, this meant that the grandchildren of everybody in court were going to be the first people to ever benefit from the litigation, apart from the lawyers present."

A legislative strategy was thus put forward which would indemnify contractors, such as Bovis, as well compensate those individuals who became injured or ill due to their involvement.

The result was the James Zadroga 9/11 Health and Compensation Act which, after more than five years of preparation and 13 months of settlement negotiations on the part of Mills and Fox, was signed into law by US President Barack Obama in January.

The Act, which received broad bipartisan support, provides for the allocation of $US4.3 billion of aid to September 11 survivors and first responders, and also provides protections for the various contractor companies, including Bovis, which responded to the civil emergency.

Both Mills and Fox said that working on the case, which received widespread media coverage in the US, was a career highlight.

"You rarely have a government body like the US Congress interested or remotely engaged in litigation of this nature and a problem of this nature," said Fox.

"Because it was 9/11 and because it had affected so many people, you did have political interest. To be able to be involved in that and watch that whole process from the vantage point we had, and for that legislation to have passed, was a real rare event, a real highlight."

Mills agrees: "The people who volunteered to work on the site were heroes, the companies that responded to a call for help ... were heroes too. In other words, this is a matter that should never have gone to litigation. To have played a part in getting it successfully resolved ... is very satisfying."

Working on the matter required a huge effort on the part of Mills and Fox, who racked up 32 trips to New York within a five-year period and spent many early mornings and weekends engaged in teleconferences with US lawyers.

"The travelling definitely took a toll on our families ... it was hard," said Mills.

"But we made some very good friends in New York and it was a fascinating matter ... it was a really big case and just fantastic to be involved in it."