Donald Trump’s decision to change definitions of domestic violence and sexual assault has rolled back women’s rights by half a century, campaigners have warned.

The Trump administration quietly changed the definition of both domestic violence and sexual assault back in April but the move has only just surfaced.

The change could have significant repercussions for millions of victims of gender-based violence.

The Trump Justice Department’s definition only considers physical harm that constitutes a felony or misdemeanour to be domestic violence – meaning other forms of domestic violence such as psychological abuse, coercive control and manipulation no longer fall under the department’s definition.

Under the Obama administration, the definition was drastically more expansive and was assessed by domestic violence organisations.

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The Office on Violence against Women (OVW), part of the Department of Justice, has amended its definition of sexual assault to also focus on criminal justice aspects.

Holly Taylor-Dunn, a senior lecturer at the University of Worcester who has been working in the field of domestic and sexual violence for 17 years, said she was shocked by the move.

The academic, who has worked in frontline roles in the domestic violence sector and used to be a domestic abuse officer for the police, argued the Trump administration’s decision turned the clock back 50 years.

“I was massively surprised and really shocked," she said. "It is quite scary how quietly it has happened. It is a massive step backwards. We have literally gone back to the 70s. We have worked so hard since the 60s and 70s to get domestic abuse and sexual violence understood as being about more than physical violence. Changing the definition to take it back to being about physical harm completely undermines what domestic abuse is about”.

“Narrowing the definition will stop victims being able to access the services they need. Prosecutions for domestic and sexual violence will also fall because they are limiting it to the most severe forms of abuse so fewer victims are likely to come forward and seek help.

“The move sets a bad example. People look to America and the UK to be progressive on issues such as these. If America does it then other countries could quite conceivably think it is an appropriate response.”

Ms Taylor-Dunn, who leads a Masters degree in Understanding Domestic and Sexual Violence, argued it was unlikely for the UK government to follow America’s lead and introduce such a measure.

Controlling or coercive behaviour in intimate or familial relationships became a new offence n the UK, punishable with a maximum prison sentence of five years, under the 2015 Serious Crime Act.

The academic said both research and victims prove that the problem is not about physical violence at its core, but noted it had been a slow process getting this form of abuse criminalised here in Britain.

Ms Taylor-Dunn said the domestic violence sector had strived to raise awareness of how complex the issue of is. She argued survivors of sexual violence and domestic violence are already treated badly by the criminal justice system due to deeply ingrained sexist stereotypes of women and the White House’s decision would only feed existing stereotypes.

Suzanne Jacob, of UK domestic violence charity Safe Lives, said: “These changes are a huge step backwards that will have very real consequences for victims and survivors of domestic abuse in the States.

"Wherever you live, if you’ve experienced domestic abuse or listened to those who have, you know all too well that physical violence is never the whole picture – and many survivors tell us that the emotional and psychological abuse takes much longer to recover from.

“Closer to home, with the publication this week of the draft Domestic Abuse Bill, this is a timely reminder that the new statutory definition of domestic abuse must encompass the different forms it can take.”

Women’s Aid identify domestic abuse as a “gendered crime” – saying that while both men and women may experience incidents of interpersonal violence and abuse, women are considerably more likely to experience repeated and severe forms of abuse, including sexual violence.

The Trump administration’s new definition says “the term ‘sexual assault’ means any non-consensual sexual act proscribed by Federal, tribal, or State law, including when the victim lacks capacity to consent.”

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In contrast, the previous definition was more expansive, saying: “Sexual assault is any type of sexual contact or behaviour that occurs without the explicit consent of the recipient. Falling under the definition of sexual assault are sexual activities as forced sexual intercourse, forcible sodomy, child molestation, incest, fondling, and attempted rape.”

The Trump government’s amendments to the definitions were first written about by Natalie Nanasi – director of the Judge Elmo B Hunter Legal Centre for Victims of Crimes Against Women at Southern Methodist University Dedman School of Law.

“What is clear is that these seemingly semantic changes, even if not yet embodied in official law or policy, are part of a broader trend toward the devaluation of women by this administration and this president,” Ms Nanasi wrote in a piece for US publication Slate.

She said the new terms may mean the OVW restricts grants for community efforts to combat domestic and sexual abuse to agencies that serve victims of crime – meaning many survivors could be left without resources. OVW may also change its education and training resources to include the new definition, no longer considering some abuse survivors as victims, she said.