Update (12/19): This post has been updated to reflect recent developments in Michigan.

Correction (12/27): This post has been corrected.

Friday’s deadly
rampage
at a Connecticut elementary school marked the 13th mass
shooting in the United States this
year
. Among the 11 deadliest shootings in U.S. history, more than half took
place in
the last five years
. During the same period, states have often relaxed
their gun laws, making it easier for individuals to obtain guns, extending the
places where concealed guns are permitted, or giving gun owners more robust
protections.

We take a closer look at some of
the more striking measures:

1. Five states allow
students to carry concealed guns on college campuses     

A March 2012 Colorado
Supreme Court decision
held that the University of Colorado could not ban students
and employees with state-issued concealed weapon permits from carrying guns on
campus. The decision overturned the university’s long-standing
gun ban
. While school policy prohibits guns at ticketed athletic and
cultural events, Boulder and Colorado Springs’ campuses now designate dorms for
permit-carrying students. (Guns are still banned in other dorms). “Not a single
student has asked to live where guns are allowed,” the Denver
Post reported last month
.

In September 2011, the Oregon Court of Appeals issued a
similar ruling
, allowing guns on campuses throughout the Oregon University
system.

Wisconsin passed legislation in 2011 allowing college
students in the University of Wisconsin school system to bring a concealed
weapon on campus grounds, parking lots and “other spaces that aren’t enclosed,”
according
to the Wisconsin State Journal
. The school can prohibit guns in buildings,
but only if signs are posted at each entrance.

A law passed by the Mississippi State Legislature in 2011 broadly
extended the places
where concealed weapons are allowed, including college
campuses, secondary schools, courthouses, polling locations, churches, bars and
passenger terminals of an airport – places previously off-limits. This
year, the University
of Mississippi
, which previously required students to leave guns in their
vehicles, began allowing students to bring concealed weapons on campus,
provided they have a concealed weapons permit and take an 8-hour training
course.

Utah
grants the least discretion
: Since 2004, the state has prohibited any
public college or university from banning concealed weapons, as campuses are considered
state property.

2. Some states now allow
you to bring guns into daycare centers, churches, and even “gun-free zones”

Last week, the Michigan Legislature passed
a law
that would allow concealed weapons in current “gun-free” zones such
as schools, day care centers, bars, churches, hospitals and stadiums. Gun
owners are required to receive eight hours of extra training before bringing
guns into these places. The bill, which has yet to be signed into law, gives private
business owners discretion to ban firearms on their property. On Tuesday, Michigan Gov. Rick Snyder vetoed the legislation since it lacked the same opt-out provision for non-private institutions like schools.

While Michigan’s legislation has gained attention given its timing
to Friday’s shooting, it’s far from the only law of its kind. As we’ve already
noted, Mississippi has also expanded the list of permissible concealed carry
locations.

Elsewhere, loaded guns in bars are now allowed in
Tennessee, Arizona, Georgia, Virginia and Ohio. Georgia lawmakers introduced
legislation
earlier this year that would expand the list of places where
you can bring in a concealed weapon, proposing to allow them in colleges, places
of worship and polling places.

Virginia, Louisiana
and Maine allow firearms
to be carried in state parks, state historic sites and state preservation
areas. Recently passed federal legislation also allows the carrying of loaded
guns in national parks
, but only if state laws don’t interject.

3. You don’t have to be 18 years old to lawfully purchase, or be sober to lawfully use, a gun in some states

In Missouri, it’s no longer a crime for an intoxicated
person to handle or fire a gun, so long as they were acting in
self-defense
.

Federal law prohibits licensed firearms dealers from selling
a shotgun or rifle to anyone under 18, or handguns to anyone under 21. Still, some
states impose minimum age limits that go below these federal limits.

For instance, in Vermont, it’s legal to sell a handgun or rifle
to 16-year-olds. It’s legal to sell a rifle to a 16-year-old in Maine, Alaska,
Minnesota or New York. In Montana, the legal age is 14, according to the Law
Center to Prevent Gun Violence
, a non-profit organization that tracks state
gun laws.

4. Eight states have
(symbolically) asserted their freedom to be exempt from federal gun regulation

Current federal gun laws set baseline standards regarding
the sale and possession of guns. For instance, the Brady Handgun Violence
Prevention Act requires licensed gun dealers to perform background
checks
on prospective gun purchasers. And agents with the Bureau of
Alcohol, Tobacco, Firearms and Explosives can conduct
warrantless inspections
of any licensed gun dealer – although, as we’ve
previously noted
, its authority has been hamstrung in recent years.

Still, eight states have passed resolutions stating that guns
made and manufactured in-state shouldn’t be subject to federal regulation: Montana,
Idaho, Wyoming, South Dakota, Utah, Arizona, Tennessee and Alaska.

The Montana gun activist behind the state’s legislation,
whom the Wall
Street Journal profiled
, explained he felt he should be “free from federal
laws requiring him to record transactions, pay license fees and open his
business to government inspectors.”

The states’ moves are basically symbolic. The states are
still following the few federal rules that exist.

But that could change. Montana Shooting Sports Association
and Second Amendment Foundation have filed a lawsuit in federal court to enforce
the law.

5. Some states want
to make it a crime for doctors and employers to ask about your gun

In 2011, Florida became the first state to enact a law prohibiting
any health care professional from asking patients whether they own guns or
store them safely. A federal judge later struck
down the law
based on free speech grounds, stating that a physician who
“counsels a patient on firearm safety…does not affect or interfere with the
patient’s right to continue to own, possess or use firearms.”

Other states have followed in Florida’s footsteps: Alabama and
North Carolina have introduced similar
legislation
in the last year.

In 2010, Indiana made
it easier
for people to store guns in their vehicles in a workplace parking
lot. A year later, Indiana passed a law allowing job applicants and current
employees to
sue
a private or public employer for requiring disclosure of firearm
ownership or use.

6. Nearly half of
states have adopted some type of “Stand Your Ground,” or “Shoot First” law

Florida
and 24 other states have enacted “Stand Your Ground” laws that expand
a person’s right to self-defense
. Under these laws, individuals no longer
have a duty to retreat to avoid confrontation in any place he or she has a
right to be.

Florida was the first state to introduce such a law in 2005
– and many other states have followed suit. The law came into national
spotlight when an unarmed 17-year-old teen, Trayvon
Martin
, was shot and killed by a neighborhood watch guard in Florida earlier
this year. The shooter, George Zimmerman, was not initially charged with a
crime; he has since been charged with second-degree murder and awaits trial.

7. A few states make
it easy for even violent felons to get their gun rights restored

The New York Times conducted
an extensive investigation
into this issue last year. The story reports that
in 11 states, nonviolent felons have automatic restoration of their gun rights
while a handful of other states allow felons convicted of violent crimes to regain
their gun rights.

In Minnesota, for instance, violent felons can petition a
court to regain their gun rights by showing “good
cause
.” There is no waiting period. In Ohio, a violent felon need only
demonstrate to a judge that he or she has “led a law-abiding life” since
they’ve left prison. In Washington State, felons can get their gun rights
restored as long as they haven’t been convicted of any new crimes in five
years. Under Washington State’s Hard
Times for Armed Crimes Act
, judges actually
have no
discretion to deny restoration
based on a felon’s character or mental
health.

Felons in other states have other ways to get their guns
back: Georgia and Nebraska have granted a high number of pardons to restore felons’
right to bear arms even for those convicted of crimes like voluntary
manslaughter or armed robbery.

And Montana makes it possible for felons to get their gun
rights restored as long as they didn’t use a dangerous weapon in the commission
of their crime.

Correction (12/27): This post originally said that you don’t have to be 18 years old to lawfully use a gun in some states. Actually, you don’t have to be 18 years old to lawfully purchase a gun in some states.