The courses of redress open to you after being falsely accused of criminal or improper behaviour will depend on the manner in which the accusations were made. If you've been damaged in any way by untrue allegations and feel that enough evidence exists to support your case, you should do all you can to clear your name and seek justice for the wrong done to you.
Perverting the course of justice
You can ask your local police force to look into pressing charges against an individual who has made a false accusation against you. The allegation would merely need to risk your arrest or conviction. After liaising with your local public prosecutor, the police may be able lay charges of wasting police time, or in more serious cases, perverting the course of justice. If your accuser is found to have lied under oath in court, proceedings for either perverting the course of justice or perjury would typically be brought without your intervention.
If an individual has made a written or oral false and defamatory statement about you, consider suing for libel or slander. If the defamatory accusation is in a permanent form, in a book, magazine or film for example, it is libel. It is slander if it is in the transient spoken form. The accusation must lower you in the estimation of "right thinking members of society generally". You won't typically be able to apply for legal aid if you decide to sue for defamation, so you'll either need to find a solicitor happy to take your case on a no-win, no-fee basis or have access to the tens of thousands of pounds defamation cases can cost. Sound out local law firms about the strength of your case.
Complain to the police if the behaviour of the individual making the false allegations against you amounts to harassment. If your accuser is regularly contacting you to level his allegations or is indulging in activities that make you feel threatened, you may be able to apply to the courts for an injunction. Harassment can also occur if the person harassing you is contacting others with his accusations.
Having false accusations levied against you can be extremely distressing. If you've been falsely accused of a crime or improper behaviour and are finding it difficult to cope, contact the Faso helpline, a voluntary organisation dedicated to supporting anyone affected by a false allegation of abuse. If false accusations have been made against you at work, contact your union for support. If you don't belong to one, consider joining up.