The Department of Justice’s antitrust division on Dec. 15 officially announced further efforts to streamline the time and cost of merger investigations. The changes are part of a 2001 merger process reform effort and closely mirror changes the Federal Trade Commission announced in February.

But there’s a big catch for merging parties that participate, and if the FTC’s track record is an indication, antitrust lawyers won’t be pushing clients to sign up. To be eligible for DOJ’s latest streamlining efforts, the Justice Department requires merging parties to agree to set a period of pretrial discovery, perhaps as much as six months, should regulators seek a court order to block a merger. That could leave merging parties open to significantly more discovery time than the government usually is granted. The FTC’s streamlining, by contrast, requires only two months of discovery.