Someone in the US would sue you in their state, which if you lost they could potentially seize your assets in that state. If you are UK based, this would entitle them to nothing upon winning. You have literally nothing to lose.
I have been manufacturing a product (not software) since 2004 and have had the pleasure of verbal threats of lawsuits a few times. After 100,000 products sold I am still waiting to see my first letter from a lawyer telling me a suit has been filed.
While the US is very litigious, the risks are not there for you. You do not have the same legal exposure as McDonalds or Wal-mart so I would not be overly concerned about it. Sell to the US as much as you want and don't worry about lawsuits. The only time you would need US insurance would be to sell to large distributors who will demand proof of insurance. For my product that used to cost $20,000 per year for insurance, now it is down to $6000 a year because of the lack of lawsuits.
I have been manufacturing a product (not software) since 2004 and have had the pleasure of verbal threats of lawsuits a few times. After 100,000 products sold I am still waiting to see my first letter from a lawyer telling me a suit has been filed.
While the US is very litigious, the risks are not there for you. You do not have the same legal exposure as McDonalds or Wal-mart so I would not be overly concerned about it. Sell to the US as much as you want and don't worry about lawsuits. The only time you would need US insurance would be to sell to large distributors who will demand proof of insurance. For my product that used to cost $20,000 per year for insurance, now it is down to $6000 a year because of the lack of lawsuits.