Legislation for no-fault divorce will be introduced as soon as parliamentary time becomes available to end the “blame game” in marital breakdowns, the justice secretary has pledged.

Changes to the existing divorce laws in England and Wales would establish a minimum six-month timeframe to enable couples to “reflect” on their decision and also abolish the ability to contest a divorce.

The limited set of grounds for divorce under the existing Matrimonial Causes Act 1973 requires an applicant to either prove their partner is at fault through adultery, desertion or unreasonable behaviour, or if both sides agree, they can part after two years of separation. In the absence of consent or evidence of fault, applicants should wait until they have been living apart for five years.

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Critics said the restrictive rules fuelled conflict by forcing one side to blame the other if they did not want to wait for years before obtaining a decree absolute divorce.

The new legislation, based on the results of public consultation, would extend the grounds for divorce while retaining the underlying concept of “irretrievable breakdown”.

David Gauke, who announced the change, said: “Hostility and conflict between parents leave their mark on children and can damage their life chances.

“While we will always uphold the institution of marriage, it cannot be right that our outdated law creates or increases conflict between divorcing couples. So I have listened to calls for reform and firmly believe now is the right time to end this unnecessary blame game for good.”

The Ministry of Justice said new legislation would be introduced “as soon as parliamentary time allows”. The need for evidence of adultery, desertion or unreasonable behaviour would be replaced by a requirement for a statement of irretrievable breakdown.

It would preserve the two-stage legal process known as decree nisi and decree absolute. There will be an option for a joint application for divorce.

After publicity over the Tini Owens case – in which the supreme court ruled last year she could not divorce her husband until a period of five years had elapsed – the government’s new bill would remove the power of a defendant to resist a divorce. Owens and her husband, Hugh Owens, had been living separate lives since 2015.

Aidan Jones, the chief executive of the relationship support charity Relate, said: “This much-needed change to the law is good news for divorcing couples and particularly for any children involved. The outdated fault-based divorce system led parting couples to apportion blame, often resulting in increased animosity and making it harder for ex-partners to develop positive relationships as co-parents.

“While divorce isn’t a decision that people tend to take lightly, we do support the extension of the minimum timeframe which will allow more time to reflect, give things another go if appropriate, and access support such as relationship counselling or mediation.”

Jo Edwards, the head of family law at Forsters LLP and a former chair of Resolution, said: “Divorce used to be perceived as an adversarial process, but increasingly couples wish to explore mediation and that is the focus of government policy.

“What this change will mean for separated couples is that they will no longer have to apportion blame for marriage breakdown (when it is rarely the fault of one spouse only), or else wait for at least two years of separation before they can have a divorce.”

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Labour has supported proposals for changing the 1973 law. The new legal framework would set a minimum timeframe of six months, from initial petition stage to the final decree absolute divorce stage. Within that time limit, the six-week gap from decree nisi to decree absolute would remain.

Records show that out of every five divorce petitions lodged over the past three years, almost three rely on conduct facts and two on separation facts. The ability to contest a divorce was used in fewer than 2% of cases. In 2018, 118,000 people petitioned for divorce in England and Wales.

Parallel changes would be made to the law governing the dissolution of a civil partnership.

• This article was amended on 9 April 2019 because an earlier version said that Jo Edwards was a former chair of Relate. That should have named the family law association Resolution, not the charity Relate.