Among the first to be threatened with legal action is two-man operation www.productsfromnz.com, which advertises and accepts payment for New Zealand-made products over the internet.
The firm received a letter from James & Wells, a law firm acting for DET, which demanded a "signing fee" of US$10,000 ($16,762) and a "royalty rate" of 1.5 per cent of website transaction value. DET also wanted 11USc for documents generated - from commercial invoices to packaging lists and import declarations.
Website founder Simon Cope said the letter threatened his business with an injunction unless it paid up for a three-year licence agreement.
"We're in our first year, we haven't even made a profit yet."
He would seek legal advice before deciding whether to remove elements of the site covered by DET's patent, or simply ignore the action.
Either way, a protracted legal fight was out of the question, said Cope, who thought his company may have been targeted due to its high rankings on internet search engines.
"We've no ability really to [fight it]. This is beyond me from a funding point of view."
Other letters have been issued to internet retailers. James & Wells lawyer Ian Finch would not reveal where they had been sent.
But DET also has internet providers in its sights. The letter to Cope outlines a licensing model that would apply to ISPs which host infringing e-commerce operators and would involve paying an upfront fee of US$25,000 covering 25 merchants and a further US$1000 for each additional e-tailer it hosts. This licence type would attract a royalty rate of 1.15 per cent of total transaction value and 5.5USc per document produced.
That threatens internet provider WebFarm, which hosts www.productsfromnz.com. Other web-hosting ISPs such as Xtra or Clearnet, which host hundreds more e-commerce websites, were potentially in the same boat.
WebFarm chief executive Richard Shearer said DET's patent would apply to any website calculating delivery payments or offering currency selections, bringing thousands of operators within its scope.
"They're basically trying to lay claim to the idea of providing a service to a customer."
Shearer feared thousands of small e-commerce operators would be unable to afford to mount a challenge against DET's claims.
The Internet Society was looking at DET's patents, but executive director Peter Macauley doubted the licence demands would stand up to legal scrutiny.
"In my experience events like these are usually someone out to make a quick buck."
Matt Adams, a partner at intellectual Property Law firm A.J. Park, said DET's patents may be successfully challenged and made invalid.
He said patents were often granted because examiners were unable to find research material that would invalidate them.
"If anyone can find any documents which describe the system or evidence of its commercial use in New Zealand prior to December 1997, that's good grounds for invalidating the patent," he said.
The men behind DET's far-reaching patents, Ed Pool and Douglas Mauer, claim to be the first inventors to "computerise the ability to do international business transactions".
The patent application originally drew Congressional objections in the US, but was granted last year.
Then, the Wall Street Journal reported that DET had been granted a controversial patent by the US Patent Office that "purports to cover any computerised process for automating international-commerce paperwork".
DET Montreal-based president Bruce Lagerman said the firm was just going after licensing revenue it was entitled to. It also had a "licensing programme" in place in the US.
"We're not going after the little guy, we're not interested in enforcement proceedings unless we have to," he said.
In an e-mail to Herald IT editor Chris Barton in October, Pool said DET had approached e-commerce software vendors it saw as likely licensees about the possibility of reaching agreement to build a "standardised platform which can be widely dispersed and shared". Nothing had come of that, forcing DET to pursue "selective enforcements".
DE Technologies' patent
A white paper describing the patented processes