Cairns' name was taken off the list of players auctioned in January for the third Indian Premier League and Modi, on his twitter page, had stated that the Kiwi was removed "due to his past record in match fixing."
Furious with Modi, the all-rounder had threatened legal action at that time but has initiated it only now.
"We are trying to have Modi served with papers. We're going through that process in India but it takes time to get through the court system. We're waiting for him, though," the 39-year-old told New Zealand Herald.
"If he decides to go to the UK we'll have him served there but it is so difficult to know his movements - especially with all the turmoil he's embroiled in. It's frustrating but we've initiated the process and just have to wait," he said.
Modi is himself facing allegations of corruption after a spectacular fall from grace but Cairns feels it still won't be easy to corner the flamboyant administrator.
"It was going to be tough anyway when you do something like this but we are left with no option. We will continue to pursue justice but at the moment he's also going through a process which needs to reach its conclusion before any judgement is passed," he said.
"We need to go through the proper channels to find out what to do next," he added.
Asked if Modi's fall has left him feeling vindicated, Cairns said it doesn't matter to him as he is focussed on getting himself cleared.
"I still have to go through this (to clear my name). There's not much emotion or anything like that but it is sad I've had to go through this process.
"The opportunity is gone now. I'm finished. There was that one window of opportunity in the IPL when I was asked to put my name forward but I'm 40 in three weeks so reality dictates, even though a return was a romantic notion," he said
Cairns, who got into diamond trade after finishing his cricket career, said he wants to give back to New Zealand cricket once the case against Modi is settled.
"Cricket's not part of my life at the moment. It'd be great to help out in a New Zealand capacity one day but because of what has happened I'm a bit of a poisoned chalice, really," he said.
"I'm a realist though and I'm not going to put people in a compromising position. Once this situation with Modi is sorted out I'm more than happy to help," he added.
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