After Democrats took control of the Virginia State Legislature earlier this month, one of the most talked about legislative gains is the possible ratification of the Equal Rights Amendment.

The ERA would grant all American citizens equal legal rights regardless of sex, banning discrimination on the basis of sex. Thirty-seven of the necessary 38 states have already passed the amendment and with Virginia’s almost assured passage of the ERA (It failed in the Virginia Senate by just one vote while under Republican control earlier this year), the ratification of this amendment is the closest it’s ever been.

That all sounds simple, right? Virginia passes the amendment, the ERA is ratified and women are (finally) granted equal protection under the constitution. But in practice, the list of legal and constitutional questions goes on and on.

But first, some history.

The ERA was first introduced to Congress in 1923 by Suffragist Alice Paul shortly after the ratification of the 19th Amendment. In 1972, nearly 50 years later, Congress passed the amendment with bipartisan support. States raced to ratify the bill (It took Hawaii just 32 minutes after Congress passed it to ratify the amendment) and within a year, 22 states had done so.

The momentum kept going until Phyllis Schlafly, a conservative anti-feminist, waged war on the ERA, saying that it would add women to the draft pool (this could happen, but nobody’s been drafted since 1973) and get rid of single-sex bathrooms (that’s not how this works). Many of her claims were false or rooted in her opposition to same-sex marriage and abortion, but her rhetoric gained national attention and the movement stalled.

By the original 1979 deadline, only 35 states had ratified the amendment, and although Congress extended it until 1982, no additional states joined. The prospect of ratifying the ERA was mostly lost until, in 2017, the Nevada State Legislature became the 36th state to do so. Illinois ratified it the following year.

So, what happens if Virginia’s Legislature passes the ERA?

Long story short, it’s complicated and we don’t know. In theory, once it’s ratified by the states, the process is supposed to be over. But the initial ratification deadline has passed and five states have rescinded their original ratification.

Supporters of the ERA claim that since Congress already extended the deadline once, they can just do it again. The US House of Representatives is currently in the process of doing just that and, on Wednesday, the House Judiciary Committee approved a resolution that would remove the prior ratification deadline. It is now up for a vote by the full House where it will likely pass due to the Democratic majority. A similar proposal sits in the Senate, but Senate Majority Leader Mitch McConnell, R-Ky, has consistently prevented progressive legislation from being put to the floor, which leaves a more uncertain future. Others argue that the deadline isn’t enforceable because it is only stated in the preamble of the amendment, not in the amendment itself. Either way, opponents of the amendment could use this as a basis to challenge the ERA.

Further complicating the situation, five states (Idaho, Kentucky, Nebraska, South Dakota and Tennessee) have rescinded their original ratification of the amendment due to anti-ERA sentiments (one included a “sunset clause” that withdrew their ratification if it didn’t gain approval by 1978). Legal precedent says this doesn’t matter (states voted to rescind their ratifications of the 14th and 15th Amendments and Congress rejected those moves, counting those states toward the total anyways). But the decision ultimately comes down to interpretations of Article V of the Constitution, which details ratification but doesn’t mention rescission and puts Congress at the center to decide on whether the amendment was validly adopted.

Why does this all matter? Don’t women already have equal protection under the law?

While legislation has expanded the rights of women over the years, the constitution currently does not explicitly forbid discrimination on the basis of sex. Opponents of the ERA have long cited the Equal Protection Clause of the 14th Amendment, saying it already covers this by forbidding states to “deny to any person within its jurisdiction the equal protection of the laws.” But there are also debates on whether sex discrimination is what Congress intended this clause to be used for when they wrote it.

According to Northwestern Associate Professor of Legal Studies Joanna Grisinger, cases of sex discrimination have mostly been framed in terms of the 14th Amendment, but the Supreme Court has deemed some kinds of discrimination worthy of higher scrutiny than others. One of the main goals of the ERA, she says, is to heighten the standard under which sex discrimination cases are viewed.

Within judicial review, there are three categories: strict scrutiny, rational basis review and intermediate scrutiny. Under strict scrutiny, used when there is a suspect classification (i.e. a law treats racial groups differently), the Supreme Court assumes the law is unconstitutional unless it is proved that the law “furthers a compelling state interest” and “the law is narrowly tailored.” Meanwhile, under rational basis review, the Supreme Court assumes the law is constitutional unless it’s clearly not, setting the bar at having a “legitimate government interest” and being “rationally related to that interest.” Intermediate scrutiny falls somewhere in between.

Currently, sex discrimination falls under heightened intermediate scrutiny, allowing states and the federal government to get away with slightly more discrimination on the basis of sex than cases where strict scrutiny is applied, according to Grisinger.

“There's been generations of women bringing cases to try to convince the Supreme Court to review sex discrimination cases on the basis of strict scrutiny, and they haven't. The ERA would do that—I think,” Grisinger said. “That’s why it’s a really big deal.”

Ultimately, what will happen if the ERA gets ratified is still unclear. The amendment doesn’t mention “strict scrutiny” and there are many questions as to what is technically considered discrimination on the basis of sex.

“If the ERA got ratified, what I think it would mean is that in some ways you'd be starting from scratch,” Grisinger said.

First, though, Virginia has to ratify the ERA. Then, we’ll figure out how complicated things actually get.