Police will face new curbs on their use of bail from Monday after they came under fire for leaving people languishing in a legal limbo for months or even years.
A 28-day limit on pre-charge bail comes into effect as part of a Government shake-up aiming to end the "injustice" of individuals being kept under a cloud of suspicion for very long periods of time.
Until now forces have not been bound by any cap on how long someone can be bailed for.
Calls for a change to the regime intensified in the wake of cases which saw high-profile figures kept on bail for months before finally learning they had been cleared.
A 28-day limit has been backed by broadcaster Paul Gambaccini, who spent a year on bail before the case against him was dropped and he was told he would not be charged over historical sex allegations.
Mr Gambaccini has previously told how he faced the "full weight of the state" for 12 months in relation to a "completely fictitious" case.
Pre-charge bail, also known as police bail, allows those under investigation to be released from custody, potentially subject to conditions, while officers continue their inquiries.
Estimates indicate that more than 400,000 people are placed on pre-charge bail every year.
Under the measures taking effect on Monday, it will still be possible for police to secure an extension beyond the initial 28-day bail period where it is deemed appropriate and necessary - for example, in complex cases.
One extension of up to three months can be authorised by a senior police officer at superintendent level or above.
In exceptional circumstances, where the police say they need to keep an individual on bail for longer, they will have to apply to a magistrate for further bail.
Bail will now only be used when it is "necessary and proportionate", and where this is not the case there will be a presumption that people will be released without bail.
Home Secretary Amber Rudd said: "Pre-charge bail is a useful and necessary tool but in many cases it is being imposed on people for many months, or even years, without any judicial oversight - and that cannot be right.
"These important reforms will mean fewer people are placed on bail and for shorter periods.
"They will bring about much-needed safeguards - public accountability and independent scrutiny - while ensuring the police can continue to do their vital work."
Andy Ward, deputy general secretary of the Police Federation of England and Wales, said it will mean a "massive change" in custody culture.
He warned the 28-day limit is unrealistic for complex investigations, saying: "Cyber-crime, for example, requires computers to be seized and equipment to be interrogated to gain evidence.
"The results for detailed forensic tests also take some time to come back."
Assistant Chief Constable Darren Martland, National Police Chiefs' Council lead on pre-charge bail, said chief officers have worked closely with the Home Office and College of Policing to ensure that forces are aware of the reforms and ready to implement them.
He added: "The legislation represents a significant change in procedure but police forces and criminal justice agencies will continue to give careful consideration to the safety of victims, witnesses and the general public, which will be balanced against the rights of a suspect."
David Tucker, Crime Lead at the College of Policing, said: "The new legislation is a significant change for policing and has sought to strike a balance between the need for police to manage investigations and not leaving a person suspected of a crime on bail for an unacceptably long period."