The police are not permitted to lie to a court. If discovered they could face serious disciplinary action. Yet that does not mean they cannot use lies to secure a conviction.
Lying to a suspect they are questioning is a common police tactic and it’s one that the law permits. Here is an example of how it might look if the police arrested you and a friend on suspicion of drugs:
They tell you that your friend has admitted you both did it
After arresting you, they will probably interview you separately. If neither of you admits guilt, they may tell one (or both) of you that the other has just confessed and said you did it. Neither of you has done anything of the sort, the police are just trying to convince you to believe that your friend has betrayed you so you may as well admit guilt.
They tell you they have undisputable proof you did it
The officers claim they have evidence, be it physical evidence, electronic evidence or even an eyewitness. They claim this evidence leaves you no chance of escaping conviction, but if you save them the hassle of a trial by admitting your guilt, they will return the favor and seek a lesser sentence for you.
The police may not have a scrap of evidence nor the remotest glimmer of hope of finding an eyewitness. They may again be lying to try and get a confession out of you.
If the police question you, whether before an arrest or after, you might feel confused about how to react. Seeking early legal guidance can help you protect your rights.