Probable CauseTerrorism presents a challenge to law enforcement since it requires police to act proactively against crimes (terrorist acts) that in many cases have not yet been committed. If the police wait, as they do traditionally, to react to terrorist crimes after they are committed, then the role of the police is that of a first responder, and an investigator. The public, however, expects police to deal with terrorism differently. This is mainly because crimes such as rape, theft, robbery and even murder target the individual while terrorism targets the public. As such, the public demands that the police act to prevent terrorism before it becomes a criminal reality.

Police officers are given the rights to search and seizure based on probable cause (Terry vs. Ohio) and to stop a person for inquiry based on reasonable suspicion. These rights were afforded to officers in order to help them prevent a crime that they believe is about to occur. To prove a crime, officers need to find evidence. However, when it comes to terrorism, evidence and weapons are not always there to find even at the execution of the attack. Let’s consider 9/11 and assume for a minute that the terrorists would have been caught prior to boarding the planes. Would we have had the foresight to articulate probable cause based on the terrorists’ behavior and if so, would we have regarded their box cutters as weapons (evidence) for a possible hijacking? Probably not.

In order to reach reasonable suspicion, officers must rely on their training and experience to come up “with an articulable and particularized belief that criminal activity is afoot”(Orleans vs. United States, 517 U.S. 690 696 (1996) Illinois vs. Gates, 462 U.S at 235). To be able to articulate terrorism-related reasonable suspicion, officers must be trained and gain experience in terrorism methods of operations. In other words, officers must be able to look at a situation or activity (suspicion) and have the capability to explain what they are seeing through their terrorist eyes. Officers who were not trained (or do not have the experience) in doing offensive surveillance, building a bomb or developing a terrorist plan among other things, will never be able to explain what they see as terrorism-related reasonable cause.

As in the case of reasonable suspicion, to develop probable cause officers need to fall back on their training and experience in order to describe “known facts and circumstances that are sufficient to warrant a man of reasonable prudence in the belief that contraband or evidence of a crime will be found” (Orleans vs. United States, 517 U.S. 690 696 (1996) Illinois vs. Gates, 462 U.S at 213,238 (1983). Finding bombs and terrorist weapons is a difficult task since almost anything can be used as a weapon and bombs appear in countless shapes and forms. In order to develop terrorist-related probable cause, officers need to rely more on information provided by the suspect than on tangible evidence. To obtain this information, officers must utilize different questioning techniques then those used when interviewing suspected criminals.

Approaching the suspect from a “law enforcement” angle will probably not work because in the case of identifiable reasonable suspicion and probable cause the suspect has yet to have broken the law. Moreover, cooperation and information is needed to establish probable cause or refute the reasonable suspicions found. Asking for an ID and checking the suspect’s criminal record is unlikely to help the officer because most terrorists avoid criminal activities and their records are therefore clean. The key to success lies in open-ended, public service oriented and inquisitive questioning geared towards refuting reasonable suspicions. In essence, the questioning that the officer conducts should resemble that of a receptionist asking politely about the intentions of a visitor entering a building and not that of an officer who has just pulled over a person for recklessly speeding on the highway.

Using non-threatening, public service oriented questioning allows law enforcement to:

  • Refute reasonable suspicions.
  • Develop probable cause, as reasonable suspicions were not refuted.
  • Deter the terrorist or arrest him/her.
  • Provide the innocent with a great public service.
  • Avoid liability and law suits.

Finally, Reasonable suspicion and probable cause are tools given to police to enforce the law even when the law has not yet been broken. Bearing this in mind, police must realize that in dealing with terrorism, prevention always supersedes enforcement and the ultimate goal behind terrorism-related reasonable suspicion and probable cause is to give police the legal justification to intervene, deter and prevent – and not necessarily to arrest and convict.


  1. Ian on January 22, 2011 at 12:07 pm

    Completed. Information was interesting.

    • Anonymous on March 16, 2016 at 12:23 pm

      This type of training is very informative, it takes you to another very important level of thinking on your feet in any situation that may arise while on duty at any given post. it make you aware and prepared for suspicious activity that normally you may not even notice, had you not been exposed to this sort of training.

  2. Kenneth Richards on May 25, 2011 at 8:02 am

    It was good info. explaining the different ways to look at suspects.

  3. Anonymous on September 6, 2015 at 8:11 pm

    So far I have learned other ways I can see through the eyes of a possible terrorist before he/she acts out.

  4. John Booth on November 22, 2016 at 4:57 pm

    A very well crafted and thoroughly legally researched commentary. However, it fails to address the issue that makes asking open ended questions of terrorist suspects problematic in the USA. Besides the 4th and 5th Amendments which make unreasonable search and seizures and being compelled to be a witness against himself in crime, 18 U.S.C. § 1001 Making False Statements makes it unlikely that any potential terrorist with a rudimentary knowledge of US law or able to use GOOGLE would answer any questions. Yes, at a police stop you do have to provide your name, but NOYA or NOYDB are also legitimate answers to any questions asked beyond your identity. I am not an attorney—nor do I play one on TV—however, I am surrounded by family members, friends, neighbors, and co-workers who are attorneys and judges. They have drilled into me since an early age never, ever say anything to government officials without counsel present. If you answer CBP’s innocuous question whether your trip was for business or pleasure upon return to the USA, that you were out of the country “on pleasure”; but, while vacation you answered business emails or met with a foreign client you just violated 18 U.S.C. § 1001 and could be looking at prison time (just ask Martha Stewart, Scooter Libby, or Jeffery Skillings). 18 U.S.C. § 1001 is the new way federal prosecutors get easy convictions (and job promotions) just like they used the tax code to convict Al Capone and other bootleggers in the 1920s. IMO revoking 18 U.S.C. § 1001 and letting people talk to government officials , instead of having them clam-up and ask for counsel, might lead to more useful interchanges that could develop criminal intent for other more serious crimes rather than lying to government officials and would be a case where less laws on the books may lead to more convictions.

  5. quamrul alam on August 30, 2017 at 5:42 am

    Good information. will help in future in performing duties

  6. Anjel castro on November 16, 2020 at 7:49 am

    The information was very informative and helpful for Security professionals.

  7. ken venske on November 24, 2020 at 8:56 am

    1. being aware 2. look at every thing

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