In November I was arbitrarily detained in London's Heathrow airport. The police asked me to hand over the passwords to all my electronic devices. Not wanting to breach client confidentiality, I declined.

This was not the first time that I have been stopped at an airport. On previous occasions, I had not given my passwords and had been permitted to go on my way. So after refusing to give my passwords, I was expecting the police to let me go. I thought I was operating within the law and in line with my rights to privacy.

But this time I wasn't allowed to go on my way. I am now facing three months in prison if found guilty of an offence under a counterterrorism power called Schedule 7.

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On the day that I was stopped in Heathrow airport, I was placed in a very difficult position: I was either going to hand over passwords to my devices or I was going to risk ending up in prison.

I decided to risk ending up in prison.

At the time, there were two reasons behind my decision. First, if I handed over my passwords I knew that I would be in breach of client confidentiality. Everyone recognises the need for trust in professional relationships between doctors and patients, lawyers and clients, teachers and students. My professional relationship with my clients also requires trust and confidentiality.

Had I been asked to disclose my personal information only, I could have made a different decision. However, I was being asked to surrender information that may be related to others - many of whom are vulnerable people seeking legal remedies to abuses they may have suffered. I felt I couldn't agree to hand over information about my clients without their consent.

Second, if I had handed over my passwords, it would have resulted in a breach of confidence in a particularly sensitive case that my organisation, CAGE, is currently investigating.

This case can lead to the prosecution of perpetrators of torture and link a number of authorities with abuses. By confiscating my devices, the police have already interfered with this ongoing investigation and if this is not resolved, it could lead to the suppression of crucial information that could bring accountability in torture cases.

Schedule 7 needs to be challenged

Schedule 7 to the Terrorism Act 2000 is a draconian legislative measure implemented at UK airports, where individuals are stopped, searched and questioned about their lives and views, in an exercise designed to gather intelligence on them.

Though it is currently applied in the framework of the so-called "War on Terror", its reach can easily be expanded more broadly, as we have witnessed through the David Miranda case.

What is clear from my experience is that authorities are trying to get a sense of an individual's beliefs. Not only is this a violation of the fundamental right to freedom of thought and belief, but there is no link between an individual's political and religious views and "terrorism". Yet this information is recorded and connections are drawn.

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There is no transparency at all about how the information gathered under Schedule 7 will be used. We don't know if it will be used to profile certain communities, or to design and develop policies, or to assist the state in criminal trials, or as secret evidence. We also do not know whether this information is shared with other agencies. For this reason, and because the powers given to the police under Schedule 7 lead to situations that resemble an interrogation and detention-without-charge, this legislative measure is a violation of the rule of law and our basic rights.

When the rule of law is disregarded or applied selectively to only a few, we need to ask ourselves what we are willing to risk for a more equal and just society – for the sake of all.

Schedule 7 is one law in a broader web of counter-terrorism measures that complement one another to criminalise ordinary people, and which can, owing to the broad language used in these texts, also be used to criminalise innocent people beyond the Muslim community.

The evidence threshold for the implementation of Schedule 7 is so low that it gives police the right to stop you without having any reason to be suspicious of you. The wording of the measure is vague and broad - for example, it doesn't say you can be stopped if you are "suspected of" terrorism. It doesn't even say if you are "involved with" terrorism, it says you can be stopped and interrogated under this act if you are someone "who appears to be a person who is or has been concerned in terrorism" (pdf).

Now "concern" - what does that word mean in this context? I mean, I could be an academic studying conflict, and I could be concerned in terrorism. I could be a journalist investigating some sort of a crime and I could be concerned in terrorism. I could be anybody.

During a Schedule 7 detainment a person may be shown photographs of other individuals and asked to give information about them. They often have to face unfounded, fearful allegations of being linked to "terrorism". It is nothing short of injustice and intimidation. This has broad implications for people who need to protect their data

This case is not only about me or CAGE. If I give in, this has broad implications for others who want to protect similar relationships and ethics in the face of an encroaching security state. For this reason, my case will set a crucial precedent not just for Muslims, but for all society.

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But beyond the effects on the individual, it is astonishing that this law has been in power, with little challenge, for 15 years. Authorities have been gathering data on individuals for this long, at the rate of between 20,000 and 50,000 people a year. Such excessive surveillance and intimidation must be challenged. This is affecting the lives of thousands and thousands of people.

The presumption of innocence is a basic right and Schedule 7 needs to be brought in line with the rule of law. I am disappointed that not more has been done. Sometimes the right thing to do is to say the law is wrong. Therefore the only correct thing to do is to resist.

The importance of privacy

Privacy is something that lies close to my heart. As a Muslim, I know that privacy is much valued in Islam and we are commanded not to spy on others. The presumption of innocence before guilt is also a founding principle of my religion.

With everything digitalised now, and with increasing threats to individual rights around the world, we have a right to demand and protect our privacy, especially responsible for protecting the rights of others in the face of oppressive authority. This notion goes to the heart of British values. Yet, it is those values that are being destroyed.

We have to ask ourselves how much we value these principles. This is about taking a risk to protect the rule of law. This is everything I have learned from CAGE.

CAGE is built on the principle that the rule of law should apply to everybody. This is a central theme of our work. When it comes to the fight against terrorism, this has been hijacked and the dialogue has been twisted so people don't think the rule of law is necessary.

Equal laws for all?

The 20th-century philosopher John Rawls imagined a scene in his book, A Theory of Justice, where a group of people would be required to design laws for the benefit of a future society - the catch being that they would die at the end of the process and be woken up not knowing what their position in the new society would be.

The reality of counterterrorism policy is that the people who are making the laws would never allow for themselves to be subjected to the same treatment - no one would wish to wake up one day with all the suspicion that accompanies being a Muslim.

READ MORE: Prevent - UK anti-terror plan 'harms children's rights'

I mentioned earlier that I refused to give my passwords to the police for two reasons: to protect my clients' confidentiality and to protect a torture survivor. Those were the two things in my mind when I was arrested. Now, after having gone through the experience of being treated like a criminal, I feel differently.

The experience has made me think that the problem is more fundamental than that: password protection should be a basic right and no one should be required to reveal their passwords if they have not been formally accused or charged with a crime.

I hope by taking this stand, I will inspire others to follow my lead. When the rule of law is disregarded or applied selectively to only a few, we need to ask ourselves what we are willing to risk for a more equal and just society - for the sake of all.

Muhammad Rabbani is the international director of the campaign group CAGE.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.