Now, online detectives can unmask 'Mr or Ms wrong' for you

Never mind whether your date is smart or good-looking. How do you know you aren't flirting with a felon?

For a small fee, a nascent crop of companies wants to help you find out by running background checks on the potential flames you encounter on Match.com, eHarmony or any of the nation's nearly 1,500 dating Web sites.

At the same time, at least two states, New York and New Jersey, have begun regulating Internet dating sites, and legal experts say they believe changes to the liability laws that protect such sites are on the horizon.

And you thought your mother was the only one who wanted to vet your love life.

The focus on background screenings comes as some 20 million Americans are using dating sites, more than double the number five years ago, according to the market research firm IBISWorld. While they are finding casual dates and even love, they are also encountering married people pretending to be single or, worse, sexual predators and convicted felons.

No one has put a number on how much violence stems from dating sites, according to groups that keep track of rape and other violent crimes, like the Department of Justice's Bureau of Justice Statistics and the National Center for Victims of Crime.

Yet plenty of crime stories begin with two people skimming each other's online dating profiles. Consider the widely reported case of Jeffrey Marsalis, a serial rapist in Philadelphia who met his victims on Match.com.

Such perils have been around since the dawn of the Internet, an ideal medium for complex cover-ups. But now that online dating is a billion-dollar industry, state officials, public safety advocates and enterprising businesses are calling for further safeguards.

Whether it is possible, however, to effectively screen people and make sites more truthful is unclear. After all, members are not always honest about their age and weight.

"What we want to do is provide some degree of safety," said Robert Buchholz, a retired New York State Police captain who, with Andrew J. Scott, a former police chief in Boca Raton, Fla., founded MyMatchChecker.com, a Web site that went live in April, enabling people to request background checks on anyone they have met on a dating site.

Mr. Buchholz and Mr. Scott, who each have more than 30 years of law enforcement experience, said that having daughters inspired them to try to make online dating safer. Their company offers a basic background search for $9.95.

In addition to Web sites, a flurry of mobile phone apps aim to make background checks as quick and easy as ordering a pizza: Just plug in a couple of facts like a name and birth date. ValiMate, the creator of the Instant National Criminal Search app, even allows users to send the results of the check to a friend for added safety.

Date Check, from Intelius, encourages users to "look up before you hook up." The app is marketed to women who want to perform a background check on would-be Romeos "in the time it takes to redo your lip gloss." (Industry professionals say that predators are usually men.)

State officials are also pushing for safer Internet dating. A law that takes effect this month in New York State, the Internet Dating Safety Act, requires sites to post common-sense safety tips, like "meet in a public place."

Assemblywoman Audrey I. Pheffer, a sponsor of the Internet law, said that it grew out of her realization that online dating had become ubiquitous, even among people she "never dreamed" would pursue romance online.

Some states have considered similar legislation but ultimately rejected it. New York's law is like one passed in 2008 by New Jersey, which also requires dating sites with a membership fee to inform users whether they do criminal background checks (most do not).

Such legislation was championed by True.com, one of the first major online dating companies to screen members to determine if they are married, felons or sexual offenders (about 2 percent of those who try to sign up are rejected, they said). Ruben Buell, the company's president, said that the type of checks it conducted were inexpensive. "You're talking pennies per check."

Still, most online dating companies question whether such checks can be effective. They contend that because state and county databases are incomplete, the checks give daters a false sense of security. Even advocates of criminal screenings concede that they are imperfect because the databases vary in quality and availability. Some counties, for instance, do not keep digital records. Others do not provide data about sex offenders.

"If I really knew that there was great ability for us to not let anyone on the site that shouldn't be on the site, I would do it," said Mandy Ginsberg, the general manager and executive vice president of Match.com. Background checks, she said, might lead daters to think everyone they encounter on the sites is safe. (Ms. Pheffer said she originally wanted background checks but decided against them for the same reason.)

Critics also point out that companies that conduct background screenings are not necessarily perfect. Some have mishandled information. Another concern involves mobile apps, which can provide personal information to people who may abuse it.

Braden Cox, a policy counsel for NetChoice, a group that advocates for Internet companies, said that background screenings were well intentioned but that most could be thwarted.

"Most people, thankfully, are good people on these Web sites," said Mr. Cox, who speaks from experience: a few weeks ago he married a woman he met on Match.com.

Dating sites have no incentive to police their members. The Communications Decency Act absolves Internet service providers of liability because the sites are not considered the publishers of the information on their pages -- their members are. The reasoning is that sites would not be able to operate if they were responsible for everything posted by their users. Lawyers have tried to get around this law, but "they usually fail," said Brian Carver, an assistant professor at the School of Information at the University of California, Berkeley. "Every start-up depends on this protection."

Parry Aftab, a lawyer and safety expert, says she is increasingly hearing about alarming cases involving online dating, like pedophiles who woo single mothers to get near their children. She expects there will be challenges to that immunity if sites accept money from members and have knowledge of criminal behavior.

Meanwhile, she advises singles to be cautious. "Don't give up your heart so fast," she said.