The American DMCA is once against used as an anti-competitive tool, largely outside its original goal of limiting Internet piracy. Cnet News is running a story where Lexmark invokes DMCA in toner suit against Static Control, a chip maker that reversed engineered the chips and protocols that Lexmark embeds into its cartridge as a barrier to prevent third parties to produce refill cartridges at lower prices. Without DMCA, they would have little chance to win this case, as reverse engineering done to favor interoperability is considered as fair use and a legal practice.
There are other interesting examples showing the versatility of the DMCA. Last month, Dow Chemical used DMCA to take down a parody site. And in November 2002, seven US retailers used DMCA to prevent Fat Wallet to operate its online price comparison service (seen on The Register which has a follow-up).
While the European Union is blindly rolling-out its own DMCA into the EU Copyright Directive, it's also
working out a directive that would outlaw the aforementioned printer manufacturers anti-competitive practices, and force them to stop shipping printers that have more security controls against third parties' cartridge than airports have against pirates.