Paris is still very much on edge after last week’s attacks on the offices of satirical magazine Charlie Hebdo, which precipitated a three-day manhunt and left 17 dead. Thousands of soldiers have been deployed amid fears of further violence, as government leaders and intelligence officials try to make sense of France's worst terrorist attack in decades.

Investigations into the massacre are ongoing, and other suspected accomplices are still at large, but questions are already swirling over how France and its neighbors will respond and what it could mean for civil liberties.

"We must respond to this exceptional situation with exceptional measures," French Prime Minister Manuel Valls said before France’s National Assembly Tuesday evening. Valls, who earlier declared France at war with radical Islam, outlined new anti-terror proposals during his address, including stronger surveillance of the internet and social media. He cautioned, however, that any new measures must not "deviate from the principles of law and values."

"Our main concern is that the French government gives the time to reflect,"

There are currently no concrete proposals on the table, and French leaders appear to be treading carefully at a time of heightened tensions among ethnic and religious groups. But the post-tragedy rhetoric from politicians in France has fueled media speculation of a new "Patriot Act à la française" — a reference to the US anti-terror legislation that was rapidly passed in the wake of the September 11th attacks. In the US, the Patriot Act laid the groundwork for unprecedented government surveillance and warrantless data gathering, at the expense of civil liberties. Following last week’s violence, rights groups fear a similar fate may await France and other European countries, where overreacting to what was widely seen as an attack on free speech could curtail much broader freedoms.

"Our main concern is that the French government gives the time to reflect," says Clémence Bectarte, a lawyer at the Paris-based International Federation for Human Rights, "to think about what happened, to think about it in an intelligent manner, and to draw conclusions that will be the result of a process. Not to react upon emotion."

Although France initially criticized the US following revelations about the NSA's data collection programs, its government has not hesitated to expand its own reach. In 2013, documents leaked by Edward Snowden revealed that France has an NSA-like data collection program of its own, and late last year, Parliament passed a law that permits the government to block any websites that promote jihadism. A law that went into effect this year allows security and intelligence services to collect data on internet users in real-time, without legal authorization, and to order telecommunications and internet companies to hand over user information.

An estimated 3.7 million people demonstrated in Paris on Sunday in support of Charlie Hebdo. (Photo credit: Dan Kitwood/Getty Images)

Intelligence authorities say such spying technology plays an important role in deterring attacks. Prior to last week’s attack, fears were already high over the large number of jihadist French nationals who had returned home from fighting in Syria and Iraq. After the shooting at Charlie Hebdo, President Francois Hollande said that "several" terrorist attacks had been disrupted in the preceding weeks. But the country's vast surveillance machinery appears to have missed this month’s attacks, despite the fact that the two chief suspects, brothers Saïd and Chérif Kouachi, were known to have links to terrorist groups overseas.

Of major concern to French and other European lawmakers is the online propaganda that terrorists groups like ISIS have begun using to recruit jihadists living abroad. France blocked some websites following last week's violence, but activists fear that such powers set a dangerous precedent for free speech.

"Mass surveillance doesn't only infringe on our privacy, but also our ability to speak freely," Jillian York, of the Electronic Frontier Foundation (EFF), wrote in a blog post this week. "The knowledge, or even the perception of surveillance, can prompt writers to think twice before touching upon a given issue."

European leaders echo calls for greater surveillance

Elsewhere in Europe, some are using the Paris attacks to call for expanded surveillance powers. On Sunday, as more than 3 million people flooded the streets of Paris in support of the free speech principles that Charlie Hebdo embodied, a group of 12 European ministers issued a joint statement calling for internet service providers to more swiftly report and remove online material "that aims to incite hatred and terror."

"We are concerned at the increasingly frequent use of the internet to fuel hatred and violence and signal our determination to ensure that the internet is not abused to this end," the statement reads, "while safeguarding that it remains, in scrupulous observance of fundamental freedoms, a forum for free expression, in full respect of the law."

Earlier this week, Prime Minister David Cameron said the government should be allowed to read encrypted messages on smartphone apps like WhatsApp and Snapchat, adding that the Paris attacks proved the need for greater government access. Experts say an outright ban on these apps wouldn't be wise or even feasible, but privacy advocates say Cameron's comments speak to larger, more troubling trends.

"Where does it stop?"

"[I]nstead of trying to address problems with the existing expansive surveillance powers, governments merely see these crises and fearful times as an opportunity to simply to ask for more," Mike Rispoli, spokesman for the London-based watchdog Privacy International, wrote in a blog post Tuesday. "Short of creating a society in which thoughts themselves are monitored and controlled by the State, no amount of surveillance powers endowed upon our governments can ensure that all acts of fanaticism and violence can be predicted and prevented."

Online rights groups hope public pressure may dissuade European governments from expanding their spying powers, though they acknowledge that recent history doesn't bode well.

"Nearly every major terrorist attack in the past couple of decades has been followed by new legislation of some kind," York said in an email Wednesday. "France just pushed through new anti-terror regulations in November, and the [prime minister] is already saying that more will be necessary. Where does it stop? These politicians haven't demonstrated the need for more surveillance, yet it's always their go-to 'solution.'"