The Ministry of Justice has revealed further details of the first major shake-up of murder laws in England and Wales for more than 50 years.
Many in the justice system believe murder laws are too inflexible
Justice minister Maria Eagle said the government would be consulting legal experts on reforming how certain defences are used in murder trials.
It follows a Law Commission report which urged murder to be reclassified to reflect levels of seriousness.
The Home Office announced plans for a full review of murder in 2004.
'Clear and fair'
Ms Eagle said the government remained committed to retaining the mandatory life sentence for murder but that the review would look at specific aspects of law "to ensure that it protects the public and provides appropriate levels of punishment for those found guilty".
"The law needs to be clear and fair so that people have confidence in the criminal justice system," she said.
"We want to have an open and inclusive debate on the issues before we bring forward firm proposals on how the law should be reformed."
The government will look at the issues of provocation and diminished responsibility as well as the use of excessive force in self-defence.
Raising the defence of provocation, for example due to infidelity, can allow defendants to plead manslaughter instead of murder.
The review will also cover offences of complicity in relation to murder and more effective procedures for dealing with infanticide.
Ms Eagle said: "The government believes it is right to deal with these crucial elements of the existing law before moving on to consider the wider structural proposals from the Law Commission."
Consultation was expected to take several months and would involve experts from inside and outside the criminal justice system, she added.
If changes to the law are needed, draft clauses will be published next summer for further consultation before any new legislation is introduced.
The Law Commission's report, Murder, Manslaughter and Infanticide, called for a new system of first and second degree murder and a more limited manslaughter prosecution.
Its proposals would mean mandatory life terms for murder being reserved for cases where an intention to kill was clear.
Under the plans, killers who intended to cause their victims "serious harm" but not to kill would be prosecuted for second degree murder and would therefore not face a mandatory life sentence.
The second tier would also include killings through "reckless indifference" and cases where the killers were provoked, suffered diminished responsibility or were under duress.
Currently all those convicted of murder must receive a life sentence but judges recommend a minimum term or "tariff".
The review, announced in October 2004 by the Home Office, before its split with the Ministry of Justice, is the first wholesale examination of murder laws since the Royal Commission on Capital Punishment which ran from 1949 to 1953.
This led to the Homicide Act, which was passed in 1957.