The Commissioner of the Metropolitan Police is calling for mandatory drug-testing at work.
Sir Bernard Hogan-Howe says that anyone failing a drug test and refusing to get help should face the sack.
He wants it to cover all occupations, but the special focus would be on teachers, transport staff and health staff working in intensive care.
The law says workers must consent to being tested, but can face disciplinary action in certain circumstances if they refuse.
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The 20-year-old was found fatally wounded on Roth Walk, near Finsbury Park, north London at around 3am on Saturday, Scotland Yard said.
Police have arrested a man wanted in connection with a burglary at the home of pensioner Richard Osborn-Brooks.
The rally comes after it emerged that the Home Office destroyed thousands of landing cards documenting the arrival of windrush-era migrants