Red Huber / Orlando Sentinel / MCT via Getty Images A photograph of Caylee Anthony is displayed on a monitor after being entered into evidence during Day 18 of the Casey Anthony trial, at the Orange County Courthouse in Orlando on June 14, 2011

Many avid followers of the trial of Casey Anthony, the Florida woman accused of murdering her 2-year-old daughter Caylee, were incensed by Tuesday’s not-guilty verdict. Unlike most others, though, Michelle Crowder did more than just fume about it.

By dinnertime, Crowder had hopped on the social-action site Change.org and launched a petition, aimed at President Obama and members of Congress, calling for a federal law that would make it a felony for parents to fail to notify police within 24 hours of a child’s disappearance or within an hour of a child’s death. Casey Anthony waited 30 days before reporting Caylee missing — one of several bizarre behaviors to which many pointed as evidence of Anthony’s guilt.

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A jury found Anthony not guilty of murder but convicted her of lying to police in the investigation of her daughter’s death. Casey initially claimed that Caylee was kidnapped by a nanny, which spurred a nationwide search before the girl’s skeletal remains were found in the woods near the Anthony family home six months later.

Within hours on Tuesday, more than 15,000 people had signed on to Crowder’s petition, “Create Caylee’s Law.” The popularity of the petition prompted an e-mail from Change.org to Crowder, an unemployed mother of two in Durant, Okla. “Every time I refreshed it, I saw more and more people were signing on,” says Change.org communications director Brian Purchia. “Late last night, I e-mailed her that this was the fastest-growing petition we’ve had on the site.”

Close to 5,000 people were adding their names each hour, and by early evening Wednesday, the petition had amassed 150,000 names. That puts it well on its way to overtaking the site’s previous record of 170,000 supporters who signed on to a campaign to end corrective rape — in which lesbian women are raped to turn them “straight” — in South Africa. That document attracted the attention of the South African government, which has established a task force to address the problem.

Indeed, less than 24 hours after Crowder began her petition, legislators from at least two states, Oklahoma and Florida, expressed their intentions to sponsor bills that would require parents to report missing children swiftly.

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On a federal level, however, it’s not clear that the proposed statute would be constitutional. The Wall Street Journal‘s Law Blog reported:

Laurence Tribe, a constitutional law scholar at Harvard, points out that criminal laws usually fall within the realm of state jurisdictions. When Congress does enact them, however, it does so under the Constitution’s commerce clause, which applies to cases that significantly impact interstate commerce. Tribe posits that the proposed “Caylee’s Law” would fail to meet that test and would not hold up at the federal level. “This is an understandable reaction to … a verdict that people feel unsatisfied with, but violating the Constitution would hardly solve the problem,” Tribe told the Law Blog. “There is no basis I can see for any congressional power to deal in this broad way with all cases of injury — and perhaps fatal injury — to children.”

But Crowder, 30, says she is hopeful her petition will yield fruit. She says she can’t know whether Anthony killed Caylee but feels certain that she had something to do with it. Crowder wonders, How could any parent not report her child missing for a month?

After poking around online, Crowder discovered that the failure to report a child missing does not appear to fall under child endangerment, child neglect or obstruction of justice laws. On Facebook, Crowder read a post urging that legislation be put in place. “I saw a bunch of people had agreed, but I thought, Is anyone really going to do anything?” she says.

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“I was raised to stand up for what I believe in, and that’s what I am doing,” says Crowder, whose concern for Caylee and other children like her is made more poignant by the fact that she doesn’t have custody of her own two daughters, ages 7 and 10.

Crowders’ daughters live with their respective fathers — Crowder was married to one, but not the other — because she says she couldn’t afford good divorce attorneys with the wages she earned working in retail and at call centers and fast-food restaurants.

The last she heard, her daughters were somewhere in northern Oklahoma. Crowder lives in the southern part of the state and has no contact with them. “I live my life hoping one day they will find me,” says Crowder. Unfortunately, that’s more than anyone can say for Caylee Anthony.

Bonnie Rochman is a reporter at TIME. Find her on Twitter at @brochman. You can also continue the discussion on TIME‘s Facebook page and on Twitter at @TIME.