Police killers are to face minimum whole-life jail terms under proposals to be unveiled by the Home Secretary in front of thousands of rank-and-file police officers.
The current starting point for anyone convicted of the murder of a police officer in the line of duty is 30 years.
But the Government is to propose that this should be increased to a life sentence without parole, Theresa May will tell the Police Federation annual conference.
Mrs May will tell the event in Bournemouth: "To attack and kill a police officer is to attack the fundamental basis of our society.
"We ask police officers to keep us safe by confronting and stopping violent criminals for us. We ask them to take risks so that we don't have to.
"That is why I am clear that life should mean life for anyone convicted of killing a police officer."
The proposals, to be put to the Sentencing Council, will form part of Mrs May's speech before she takes questions from officers on the floor in what is likely to be a heated session.
Home Secretary Theresa May will give a keynote speech at the Police Federation conference today. Last year, she was heckled, booed and faced calls to resign.
Mrs May is to unveil proposals to to ensure people who kill police face minimum whole-life jail terms.
The Government risks making it harder to catch criminals like fugitive Andrew Moran with its stance on Europe, the shadow home secretary expected to say today.
Moran, 31, from Greater Manchester, was arrested in the Spanish resort of Calpe in Alicante on Friday after being on the run for more than four years.
Yvette Cooper will tell the Police Federation annual conference that a proposal to withdraw from the European Arrest Warrant agreement plays into the hands of criminals and ties the hands of police.
Ms Cooper will say Moran, who agreed to return to the UK to face sentencing at a hearing in a Spanish court yesterday, was arrested under the "very warrant the Government wants to rip up" and "abandon".
"The Tory party's hysteria over Europe risks tying themselves in knots. More worryingly it risks playing into the hands of criminals and tying the hands of the police.
"By trying to sound tough on everything with Europe in the title, the Government will end up being soft on crime".