(CNN) -- Much attention has been paid to the defeat in Congress of proposals to ban assault weapons and expand background checks for firearm purchases.
But states have been busy passing gun laws of their own in the wake of the December 14 massacre in Newtown.
At least five states have tightened gun laws, including Connecticut, Colorado and New York, while more than a dozen others have loosened them. Several states are still considering measures.
Connecticut added more than 100 guns to its list of banned assault weapons, banned armor-piercing bullets and limited gun magazines to a capacity of 10 rounds.
Kansas adopted a law saying that federal statues that violate the Second Amendment are no longer applicable in the state, and that any federal agent who tries to enforce federal gun laws faces jail time.
At least eight states -- including Arizona, where a 2011 mass shooting killed six people and left then-Rep. Gabrielle Giffords badly wounded -- have passed laws that exempt gun permits from public records. Those laws were largely in reaction to a suburban New York newspaper that published an online map pinpointing the addresses of people with gun permits.
Meanwhile, states where new gun control measures have been enacted already face court challenges by gun rights supporters.
Below is a state-by-state summary of key parts of new gun laws that are in effect or will take effect this year:
States that have loosened gun laws:
Alabama: Residents can carry loaded guns in their vehicles to their workplace if they have a concealed-carry permit. If they don't have a concealed weapons permit, they can bring a gun to their car but it must be unloaded and locked away.
Arizona: There should be no record of "the identifying information of a person who owns, possesses, purchases, sells or transfers a firearm." In addition, police departments that conduct gun buyback programs to get guns off the street must sell the guns instead of destroying them.
Arkansas: Guns are allowed in church, and licensed faculty and staff at public universities and colleges can carry concealed handguns. Employees of bars and liquor stores who have concealed permits can bring their guns to work. Prosecutors and deputy prosecutors can now carry a firearm, as can members of the parole board, their investigators and a parole revocation judge. A list of residents with concealed weapons permits will no longer be part of the public record. In addition, the governor can no longer suspend the sale of guns during a declared disaster emergency.
Idaho: Concealed gun permits are no longer public record, and the state recognizes concealed permits from any state.
Kansas: Federal gun laws will no longer be enforced, and any federal agent who tries to enforce federal laws faces arrest, jail time and a fine. The state also now recognizes concealed carry permits from any state.
Kentucky: Citizens can openly carry guns in formerly banned public places, including the State Capitol, city halls, council chambers, libraries, community centers, zoos and parks. The only exceptions to the law are schools and colleges.
Maine: Names and other personal information of people with gun permits are no longer part of the public record.
Mississippi: Concealed weapons permits are no longer public record, and people can now carry partially visible pistols. A new grant will assist law enforcement agencies in providing additional school resource officers in primary and secondary schools.
North Dakota: Guns are now allowed in churches.
Oklahoma: Recognizes any valid concealed weapons permit from any state. People who seek certain renewals of gun permits will no longer be fingerprinted, effective November 1. District court judges, the state attorney general and assistant attorney generals can carry firearms, effective November 1.
South Dakota: Local school boards can train and arm employees, including volunteers, inside the classroom. Concealed weapons permits are now valid for five years, instead of four.
Tennessee: Gun owners with concealed permits can keep guns in their vehicles in public or private parking lots effective July 1. Concealed weapons permits are no longer part of the public record.
Utah: Concealed weapons permits are no longer part of the public record. A person currently not allowed to possess a firearm because of mental health reasons can petition the state for the right to bear arms.
Virginia: Concealed weapons permits are no longer part of the public record, but the state can still release "statistical summaries, abstracts, or other records containing information in an aggregate form."
West Virginia: Recognizes concealed permits from additional states. Guns can no longer be seized during a declared emergency.
Wyoming: Judges can carry a gun into a courtroom, effective July 1.
States that have tightened gun laws:
Colorado: The state where 12 people were killed and 58 wounded in a mass shooting at a movie theater in Aurora in 2012 made background checks mandatory for all gun purchases and has limited magazine capacity to 10 rounds.
Connecticut: More than 100 guns have been added to the state's list of banned assault weapons. Armor-piercing bullets are banned, and gun magazines are limited to a capacity of 10 rounds. Gun owners who currently own magazines capable of holding more than 10 rounds can keep them but must register them with the state.
All firearms sales, including ones at gun shows, must go through background checks. Stiffer penalties for illegal possession and trafficking of guns have been authorized. Also, the nation's first statewide registry of people convicted of crimes involving the use or threat of dangerous weapons is being created; such information will only be available to law enforcement.
Delaware: Background checks on all gun purchases are required, assault weapons are prohibited, and magazine capacity is limited to 10 rounds.
Maryland: The state banned the sale of 45 types of assault weapons, including the AR-15, and limited magazine capacity to 10 rounds. Residents purchasing a handgun must be fingerprinted and go through safety training. A single automated gun application process between gun dealers and Maryland state police has been established.
New York: High capacity magazines are banned. Assault weapons must be registered within the state, including those already owned by residents. All gun buyers must undergo background checks, including at gun shows and private sales except transactions among immediate family members. Anyone who purchases ammunition must also undergo a background check. Sales of assault weapons on the Internet are banned.
Mental health professionals who believe a mental health patient might be a danger to society must report that information to a health care director, who must then relay what they determine to be serious threats to the state Department of Criminal Justice Services.