Dwayne Holman, 39, was jailed for five months on Tuesday after pleading guilty in Portland Magistrates Court to two counts of assaulting police.

The man has a history of similar offending, including assaulting and resisting police in 2018.

Then in November last year, emergency services were called to a cliff at the end of Portland's Daniel Street after a car crashed, falling 50 metres down an embankment about 1.55am.

Holman heard the collision and attended to find the victim was his close friend.

Police body-worn camera footage initially showed the man holding up branches to help emergency services access the scene.

But when asked to leave, Holman threw a branch at First Constable Lize-Marie Mitchley.

An arrest was attempted by the first constable and Sergeant Andrew Dunlop but Holman resisted.

During a subsequent wrestle the offender sat on First Constable Mitchley's neck and head, forcing her face into the ground and preventing her from breathing.

She deployed a taser but it struck Sergeant Dunlop, causing him to be briefly incapacitated.

Holman was eventually tasered, hit with OC spray and handcuffed.

The court heard Sergeant Dunlop suffered cuts, significant swelling and underwent a total knee replacement.

The police officer of 22 years had a lengthy period off work and still experiences limited feeling in his thumb.

First Constable Mitchley, who'd been in the force for a little over two years, left Portland to not be reminded of the incident.

Police prosecutor Sergeant Angela Fitzgerald said it was particularly concerning the assaults happened at a collision scene.

"They were there to save someone's life and wouldn't have expected to be assaulted. They weren't attending a violent pub brawl," she said.

She said body-worn camera footage showed the assault was protracted, lasting about 30 minutes.

"The members when dealing with him were nothing but empathetic, restrained and professional," Sergeant Fitzgerald said.

"For him to turn on them in the fashion he did was unexpected and aggravating."

Kerry Schroeder, representing Holman, said her client was highly emotional at the scene of the crash where his friend was believed to be seriously injured.

But magistrate Franz Holzer said the man had caused serious injuries to the police members, both who had reported significant and longstanding impacts on their lives and careers.

The court heard Holman refused to consent to a community correction order, which could have seen him serve his sentence in the community.

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