NASHVILLE (AP) — Tennessee's Supreme Court was asked Wednesday to decide whether the state's voter ID law deprives people of the right to vote or if it's a necessary safeguard to prevent election fraud. And in a related issue, the court must determine whether a city-issued library card with a photo can be used as identification to vote.

The court heard arguments from the city of Memphis and two residents who are challenging the law. The city and the individual plaintiffs sued the state last year after election officials refused to accept a city-issued library card with a photo as voter identification.

The state attorney general's office argued that that the library card is issued by the city while the state's voter ID law passed in 2011 requires either a state-issued photo ID, federal identification or an ID issued from another state. Janet M. Kleinfelter, a deputy attorney general, also said the law was not so onerous that it would deprive people of the right to vote.

But attorneys representing the city said the votes of 650 people have not been counted in the last two elections because they lacked the proper identification.

"They were deprived of the right to vote," Nashville attorney George Barrett said. Barrett argued that the statute violates the Tennessee Constitution, which only requires someone to be a U.S citizen, a resident of the state, at least 18 and properly registered in order to vote.

Kleinfelter disagreed that 650 people were deprived of the right to vote. People who don't have the proper identification to vote are allowed to cast a provisional ballot and have two business days to present proper ID to their county election commission so their vote will be counted. Some of those people, Kleinfelter said, might not bother to make the trip to present an ID if they think their vote won't matter - either because their candidate won in a landslide or lost overwhelmingly.

She a lso argued that one of the women who wanted to use a library card in the case could have gone across the street from her polling place and gotten a state issued-ID.

But Justice Sharon Lee pointed out that she is from Monroe County and residents have to travel outside the county to get a voter ID.

She and other justices questioned whether it would be OK for a mayor of a city to issue a voting ID and they wondered whether accepting the library cards would open the way for all kinds of city or county-issued identification to be accepted.

"You can see it's sort of a slippery slope," Lee said.

State law does recognize identification from other state governments, prompting Justice William Koch Jr. to ask: "What about the guy with the fishing license from Alabama?"

Some of the justices wondered whether it's more important to be properly registered and whether it's easier to commit election fraud by voting absentee.

Kleinfelter said voter fraud is not widespread in Tennessee.

The Tennessee Court of Appeals has upheld the state voter ID law as constitutional, but also allowed Memphis residents to use the library card as identification to vote. The Supreme Court said last year that the library card could be used while the court was considering the case.

It's expected to be several months before the high court makes a ruling.