"Women in Politics: Why we Need the Equal Rights Amendment"
What women have depended upon is statutory or changeable law from the Civil Rights movement of the 1960s. That law is still on the books but key parts are increasingly unenforceable; a law is only as good as its enforcement.
Let's take the equal pay law as an example. During World War II, there was an agency proposal to pay women equally in order to recruit Rosie the Riveter and her companion workers into nontraditional jobs. The war ended before it was implemented, but the idea became law in 1963, and was bolstered by Title VII of the Civil Rights Act of 1964.
In 2007, the Supreme Court in Ledbetter v. Goodyear ruled against Lily Ledbetter's equal pay case. After 20 years of work, she learned that she had been paid thousands less than men in her job. The degree of the current Supreme Court's hostility can be judged from their reasoning: that Ledbetter should have filed her claim within 6 months of the first unequal paycheck, despite the fact that she had no way of knowing her unfair treatment. Two years later, Congress "restored" the Equal Pay law. However, in a 2011 case brought against Wal-Mart for unequal pay and promotion, the Court said that the plaintiffs had to prove "intention" to discriminate, a virtually impossible bar.
The same type of on-and-off-again cycle has happened with discrimination against pregnancy and equal opportunity in education and sports, but if a plaintiff has to prove intention, the law is a hollow shell.
An Equal Rights Amendment would provide a permanent and high standard ("strict scrutiny" in legal terms) for judging sex discrimination. It would shift the burden of proof from the plaintiff to the opposition.
The years since the early Civil Rights laws like Equal Pay that helped women greatly have proven how quickly these advancements can be eliminated in all but name. That's why the permanence and strength of the ERA is needed.