WASHINGTON — The data breach at Target Corp., which exposed millions of credit card numbers, has focused attention on the patchwork of state consumer notification laws and renewed a push for a single national standard.
Most states require retailers to disclose data breaches, but laws vary wildly. Consumers in one state might learn immediately that personal information has been exposed, but that might not happen in another state, and notification requirements for businesses depend on where customers are located.
Attorney General Eric Holder has joined the call for a nationwide standard, but divisions persist, making a consensus questionable this year.
‘‘We’re stuck with the state-by-state approach unless some compromise gets done at the federal level,’’ said Peter Swire, a Georgia Tech privacy expert.
There are obstacles to a straightforward compromise:
■ Consumer groups don’t want to weaken protections in states with the strongest laws.
■ Retailers want laws that are less burdensome to comply with and say too much notification could cause consumers to tune out the problem.
■ Congress is looking at different proposals for how any federal standard should be enforced and what the threshold should be before notification requirements kick in.
Target, the second-largest US retail discounter, said 40 million credit and debit card accounts were exposed between Nov. 27 and Dec. 15. It went public with the breach on Dec. 19, several days after it learned of the problem. Since then, sales, profit and Target’s stock price have dropped, its chief information officer has resigned, and banks and retailers are facing continued scrutiny about what more can be done to protect consumer data.
Last month, Holder urged Congress to adopt a national notification rule, with exemptions for harmless breaches.
‘‘This would empower the American people to protect themselves . . . It would enable law enforcement to better investigate these crimes and to hold compromised entities accountable when they fail to keep sensitive information safe,’’ he said.
Currently, 46 states and the District of Columbia have their own notification laws, according to the National Conference of State Legislatures.
Proposals now before Congress would require notification. But there are differences in what information the notification would provide, the threshold for notifying regulators and law enforcement, and the proposed enforcement. Some bills seek criminal penalties for deliberately concealing a breach; others do not.
Consumer groups fear any national standard could turn out to be weaker than the strongest state laws, such as California’s, which requires a business or state agency to notify any resident whose data were improperly obtained.
‘‘From industry’s perspective, whether you’re a bank or a merchant, you don’t want to have to notify consumers,’’ said Ed Mierzwinski, at the US Public Interest Research Group. ‘‘They want to preempt, or override, the best state laws.’’
Retailers say they do support a federal standard but one that would be triggered when sensitive material has been exposed — as opposed to, say, customers’ shoe sizes — and when there’s a risk of theft or fraud.
Retailers remain at odds with financial institutions. They say banks need to upgrade security on credit cards. Banks say retailers need to do more to enhance their own security.
‘‘There’s no agreement in the private sector among the major players about what their responsibilities are,’’ said Senator Tom Carper, Democrat of Delaware.