While some American politicians and commentators are speculating that the mass school shooting in Newtown, Conn., may be the "tipping point" that prompts a significant tightening of U.S. gun laws, any new legislation would most likely still face substantial political and legal hurdles.

Over the weekend, Democratic Senator Dianne Feinstein said she would introduce legislation early in the new year that would include a ban against new assault weapons, in effect re-introducing a ban that was allowed to expire in 2004.

And on Monday, Democratic Senator Frank Lautenberg said that he would reintroduce legislation in the next Congress to ban the sale of large capacity ammunition magazines.

But whether those proposed laws actually make their way through Congress remains to be seen.

"On gun control, at the moment, it would be very, very surprising if anything particularly drastic were able to get through Congress," said George Mason University law professor Nelson Lund.

"It's possible, though I still think fairly unlikely, that if the emotional public reaction to this shooting is sustained for a while, it's possible you might be able to get some minor symbolic thing in Congress.

"But I personally wouldn’t expect much more than that and even that is unlikely," Lund said. "The emotional reaction from the public tends to die down long before Congress can get around to doing anything."

Calls for tougher gun laws have grown following the shooting deaths of 20 children and six adults at Sandy Hook Elementary School in Newtown on Friday.

But while the Democrats are felt to be more amenable to legislating tougher gun laws, the House of Representatives is controlled by Republicans. What's more, even in the Democratic-controlled Senate there are still a number of Democratic senators who are supporters of gun rights.

Though some, including Senate Majority Leader Harry Reid, who has consistently opposed a ban on assault weapons, have now said they are open to a discussion on the issue.

Visitors light candles at a memorial for the shooting victims of Sandy Hook Elementary School in Newtown. (Jason DeCrow/Associated Press)

"I'd be surprised if it could get though the Senate. I'd be shocked if it could get through the House," Lund said. "There are just too many members in both houses who would be politically imperiled by voting for something like that."

As the National Journal magazine points out, a number of proposed gun-control bills were introduced in the recent Congress, but none of them made it out of committee.

Those included a bill banning the sale of large-capacity ammunition magazines; a bill requiring criminal background checks on all firearm transactions occurring at gun shows; and a prohibition against carrying a firearm near a place where a federal official is holding a public event. The latter, an obvious reference to the shooting of former congresswoman Gabrielle Giffords in 2011.

President Barack Obama has also said he favours the reinstatement of the ban on assault weapons but has so far shown little appetite to pursue it.

The last major federal gun legislation was passed in 1994 under the Bill Clinton administration. The law, which placed a 10-year ban on assault weapons, took a political toll on Democrats in the midterm elections that year, Lund said.

"They had to work very hard to do it. The Democrats controlled both houses of Congress and the leaders in Congress used party discipline pretty hard to get that through.There were a lot of Democrats who did not want to vote for it and they were pressured into doing it. Some lost their seat as a direct result."

In the end, critics questioned the effectiveness of the ban while others complained that the law was full of loopholes. It eventually expired in 2004, with no political will to keep it going.

"Politicians have learned that the people who strongly favour gun rights have long memories," Lund said.

"It's not so much that a majority of people favour gun rights. What makes this so politically perilous for a lot of politicians is that a lot of people who strongly support gun rights are in their district and they vote. And they vote on that issue."

However, in 2007, following the Virginia Tech shootings, in which 32 people were killed, Congress did pass what some hailed as the first major federal gun control law since the assault weapons ban.

Then president George W. Bush signed into law the National Instant Criminal Background Check System Improvement Act. The legislation, which was not opposed by the National Rifle Association, the biggest of the American gun lobbies, attempted to, among other things, prevent those with mental health issues from acquiring a firearm.

But federal laws in the U.S. are relatively lax and the most stringent gun laws are enacted at the state level, Lund said. And these laws differ state by state.

Connecticut, for example, is one of a handful of states that has an assault-weapons ban in place, but it is one that is easily gotten around and bans only certain models.

Forty states make it easy for people to carry a gun in public, but in states like California and New York, local and state regulations make it difficult if not impossible to get a licence to carry a weapon.

"The only thing that the Supreme Court has said is that law-abiding people have a right to keep a handgun in their home for self-defence," Lund says. "So that means, as a legal matter, total bans on civilian firearms are off the table. But a lot of states have laws that are much, much stricter or burdensome than the federal law."

With files from The Associated Press