Public police forces are choosing not to investigate major accidents at CN and Canadian Pacific Railway, including recent crude oil train crashes and deadly derailments.

Instead, the RCMP, Ontario Provincial Police and other forces routinely defer to little-known federal railway police run by CP and CN, leaving the companies to investigate themselves with no outside police looking into potential criminal negligence.

It's infuriated some families of workers killed on the railways who claim a "double standard" where outside police are willing to move in to clear blockades along Canada's rail lines but routinely don't investigate rail corporations in the event of major disasters or fatalities.

Instead, outside police defer to the railways, which since the 19th century have employed their own fully authorized federal police forces, which have all the powers of regular police.

But unlike public police, rail police lack any civilian oversight, are paid for by private companies and are not governed by any formal police act.

In three recent derailments that leaked millions of litres of crude oil in Saskatchewan and Ontario, no police agencies investigated.

In early December, when 33 tanker cars crashed and exploded southeast of Saskatoon, CP Railway said their police service did not investigate and referred inquiries to the RCMP.

Two months later, just seven kilometres down the same CP rail line, a second crude oil train derailed and exploded, forcing evacuation of the hamlet of Guernsey.

Neither CP police nor the RCMP investigated, despite striking similarities in the crash on the same rail line where regulators had earlier found problems with the track.

In northern Ontario, neither OPP nor CN Police are investigating the derailment of an oil train near Fort Frances on Feb. 18, 2020, involving 26 crude oil tanker cars.

Even with 3 major derailments and arsons occurring during the Wet'suwet'en Solidarity protests & #ShutCanadaDown, the RCMP say they’d have to be invited to investigate.

With files from CBC News