No, it isn't. You clearly do not understand what I am posting. This much is clear from the fact that you immediately confuse "arrest" and "charge". They are NOT the same thing and they are NOT (and have never been) based on the same levels of evidence.So length of detention should be determined by the state of technology and resources? If a new technique is developed that takes two months to carry out, should the length of detention be extended to two months? This kind of investigation can be carried out after charge. The point is that there should be enough evidence for a prima facie case before anyone is arrested. Otherwise, you are simply depriving innocent people of their liberty on the say-so of a policeman's hunch. Sorry, d-b, but my experience with the police has shown me that most coppers are simply not bright enough to be entrusted with such power.
ETA: What is nuts is the idea that a person's right to liberty should be a movable feast, to be changed at the whim of the authorities as technology improves, as decided by coppers. What you advocate is a police state, nothing less.
Arrest is, and always has been, based on reasonable grounds to suspect. This is usually pretty much prima facie case ... but not always. I could provide you with lots and lots of situations in which you would agree that arrest is more than justified but there is not a prima facie case (that term has a specific legal meaning and, effectively, it is sufficient evidence that a jury, properly directed, could convict).
The level of evidence required for charge (and, hence, the length of time needed to establish that level of evidence in an admissible format - statements, transcripts of interviews, scientific test results, etc.) has changed. Until the introduction of the CPS in the mid-80s (at the same time as, but not directly connected with, the introduction of PACE) the test for charging was the prima facie case. This meant that charges could be laid at a very, very early stage in an investigation. What then happened was that the prosecution applied for (and were invariably granted) remand after remand after remand whilst the investigations were completed. As the world became more complex, and as the ines of enquiry became more complex and took longer to complete, these remand periods got longer and longer. If you go back to the 80s you will find it was not at all unusual for a defendant to be charged within a few days ... and then spend three years in custody pending trial.
The CPS brought with them a variety of time limits for proceeding with a case which had the effect of truncating the time available for investigation between charge and trial. They also brought in a test for proceeding with a case (which they applied very early after charge and which they have now moved back to pre-charge) of the case being ready to go with a conviction more likely than an acquittal.
"Charge" therefore now requires way, way more than a prima facie case.
There also used to be something called the "holding charge" - this would be where there was sufficient evidence to charge a lesser offence (perhaps possession of a firearm) which would then be used to remand the defendant in custody whilst enquiries continued into other, more complex serious offences (perhaps murder or armed robbery). That has been outlawed in the UK since the introduction of the CPS.
This has meant that dangerous offenders are released on investigative bail, pre-charge in far, far more cases than was ever the case before. Some commit more offences. Some go missing. Some interfere with witnesses or other evidence, things they couldn't do if in custody. To a certain extent this has been addressed by the CPS allowing charge in serious cases where there are substantial fears of further offences, etc. without the case being ready to go ... but that is not the norm.
Between arrest and charge comes investigative detention. Investigations take time - you simply cannot do all that is required (most of which cannot be argued with as it demonstrably provides "best evidence" to the Courts and thus maximises the chances of a just outcome), to the level it is required (again most of which cannot be argued with) in a few hours or days. The options are therefore:
1. Keep the high level of evidence required to justify charge and live with extended periods of investigative detention.
2. Keep the high level of evidence required to justify charge and live with the fact that lots of dangerous offenders will be released on bail whilst investigations continue (and thus be free to abscond / commit further offences / interfere with witnesses).
3. Reduce the level of evidence required to justify charge to prima facie case and permit post charge interviews to deal with evidence coming to light subsequently and live with the fact that there will be more post-charge delay before trial.
4. Reduce the level of evidence required to justify charge to prima facie case and NOT permit post charge interviews about new evidence and live with the fact that you are not presenting the best evidence to the Courts at trial, not least because you have not allowed the defendant to explain any of this new evidence and open up new lines of enquiry which may undermine it.
What you simply cannot have is no significant opportunity to investigate pre-charge, trials as soon as possible after charge AND thorough, competent investigations. It just doesn't work. You cannot shrink time and investigations take time. End of.
) but broadly speaking it is do-able.
