Actress Alyssa Milano standing behind the Fearless Girl statue, speaks in favour of the adoption of the Equal Rights Amendment (Image: AP/Mark Lennihan)

"Equality of rights under the law shall not be denied or abridged by the United States or by any State on account of sex."

So reads the pending Equal Rights Amendment (ERA) to the Constitution of the United States. Sounds reasonable. Who could argue with that?

Plenty of people, as it happens. The struggle to affirm equal constitutional rights for men and women has been waged for nearly a century. First proposed in 1923, just three years after the 19th Amendment gave women the vote, passage of the ERA has been a pitched battle.