The Military Police Complaints Commission will tell a Commons committee next week that the bill would give the Canadian Forces' second-in-command the ability to direct investigations into soldiers under his or her command.
MPCC chairman Glenn Stannard has submitted a brief to the Commons defence committee saying Bill C-15 goes against a two-decade trend of making military police more independent.
The clause prompting the MPCC's concern — found in Sec. 18.5 of the bill — allows the vice chief of defence staff to "issue instructions or guidelines in writing in respect of a particular investigation" to Canada's top military policeman, the provost marshal.
"Such an express authority is inconsistent with existing arrangements in place since the period following the troubled Somalia deployment which specifically sought to safeguard MP investigations from interference by the chain of command," said the MPCC brief.
"Subsection 18.5(3) runs counter to various efforts over the years to shore up public confidence in the independence of military policing."
The MPCC keeps an eye on military police by ensuring their investigations are thorough and fair. The government created the watchdog following accusations that the military blocked an investigation into the killing of a Somali teenager by Canadian soldiers.
Senior government and military officials said the independence of military police needs to be balanced with the ability of commanders to hold them accountable, especially during war.
"Bill C-15 seeks to achieve an appropriate balance between these two needs by ensuring that those responsible for mission success remain accountable in doing so while the equally important principle of police independence is upheld," Jay Paxton, a spokesperson for Defence Minister Peter MacKay, said in an email.
C-15 contradicts an agreement signed in 1998 between the vice chief and provost marshal, said the MPCC.
That agreement, known as the "accountability framework," outlines that the vice chief "shall not direct the [provost marshal] with respect to specific military police operational decisions of an investigative nature."
It goes on to say, "discussions with the [vice chief] of specific details of any investigation are to be avoided unless specific circumstances warrant attention of management."
"I hear a lot about the accountability framework and it is just that — it's a policy that can be changed," said Maj.-Gen. Blaise Cathcart, who holds the job of judge advocate general as the military's top lawyer.
The military needs C-15 to cement policies like the accountability framework in legislation, he said.
"This is giving clarity and certainty in law by Parliament as to the roles and responsibilities so there's no arbitrary abuse of the process as there could theoretically be with the policy framework," said Cathcart.
It's not the first time lawmakers have tried to reform the military justice system.
Bill C-7 was abandoned when Prime Minister Stephen Harper prorogued Parliament in 2007. C-45 and C-41 both died when elections were called in 2008 and 2010.
The MPCC isn't alone in speaking out about what they said are dangerous consequences if C-15 goes through.
"The vice chief of defence staff could actually interfere with an investigation by shutting it down," said NDP defence critic Jack Harris. "I have a lot of trouble with it."
But that simply won't happen, said the government.
"Bill C-15 provides for an important safeguard that will ensure an appropriate degree of investigative independence is maintained by the Canadian Forces provost marshal and the military chain of command," said Paxton.
That safeguard is a clause letting the provost marshal go public with any direction she or he gets from the vice chief. They can also complain to the MPCC if they think an investigation is being shut down when it shouldn't be, said Paxton.
"Once it's in the public then we're all accountable — including the minister — ultimately, to Parliament," said Cathcart.
Liberal defence critic John McKay said he's not convinced, comparing it to the civilian police.
"Suppose the prime minister could yank any RCMP investigation he wanted to," said McKay. "There would be outrage."
And although he said he understands why the military needs special rules, C-15 takes it too far, McKay added.
"If it's not really necessary for a civilian investigation, I'm not persuaded that there's a compelling reason for it to be necessary for a military investigation," he said.
"We have within our memory banks the Somalia inquiry. That was not a good time for either the military or the government. There was a lot of interference by senior officers. We appear not to have learned that lesson."