Port authorities were acting within their duties and functions when it used x-ray scanning machines for inspection of passengers’ bags.134 When the results of the x-ray scan revealed the existence of firearms in the bag, the port authorities had probable cause to conduct a search of petitioner’s bag. Notably, petitioner did not contest the results of the x-ray scan.

IV

Was the search rendered unreasonable at the second point of intrusion—when the baggage inspector opened petitioner’s bag and called the attention of the port police officer?

We rule in the negative.

The port personnel’s actions proceed from the authority and policy to ensure the safety of travelers and vehicles within the port. At this point, petitioner already submitted himself and his belongings to inspection by placing his bag in the x-ray scanning machine.

The presentation of petitioner’s bag for x-ray scanning was voluntary. Petitioner had the choice of whether to present the bag or not. He had the option not to travel if he did not want his bag scanned or inspected. X-ray machine scanning and actual inspection upon showing of probable cause that a crime is being or has been committed are part of reasonable security regulations to safeguard the passengers passing through ports or terminals. Probable cause is:

reasonable ground of suspicion supported by circumstances sufficiently strong in themselves to induce a cautious man to believe that the person accused is guilty of the offense charged. It refers to the existence of such facts and circumstances that can lead a reasonably discreet and prudent man to believe that an offense has been committed, and that the items, articles or objects sought in connection with said offense or subject to seizure and destruction by law are in the place to be searched.135

It is not too burdensome to be considered as an affront to an ordinary person’s right to travel if weighed against the safety of all passengers and the security in the port facility.

As one philosopher said, the balance between authority and an individual’s liberty may be confined within the harm that the individual may cause others. John Stuart Mill’s "harm principle" provides:

[T]he sole end for which mankind are warranted, individually or collectively, in interfering with the liberty of action of any of their number, is self-protection. That the only purpose for which power can be rightfully exercised over any member of a civilised community, against his will, is to prevent harm to others. His own good, either physical or moral, is not a sufficient warrant. He cannot rightfully be compelled to do or forbear because it will be better for him to do so, because it will make him happier, because, in the opinions of others, to do so would be wise, or even right. These are good reasons for remonstrating with him, or reasoning with him, or persuading him, or entreating him, but not for compelling him, or visiting him with any evil in case he do otherwise. To justify that, the conduct from which it is desired to deter him must be calculated to produce evil to someone else. The only part of the conduct of any one, for which he is amenable to society, is that which concerns others. In the part which merely concerns himself, his independence is, of right, absolute. Over himself, over his own body and mind, the individual is sovereign.136

Any perceived curtailment of liberty due to the presentation of person and effects for port security measures is a permissible intrusion to privacy when measured against the possible harm to society caused by lawless persons.