Back in the early days of my mental health career, I first came across common law in the form of two handles on a door. To leave the psychogeriatric ward, both the lower and upper handle (the latter at head height) were operated simultaneously. This ploy was to prevent confused residents from going out and possibly getting chilled to the bone, lost, or hit by a car. There was no need for them to be 'sectioned' under the Mental Health Act. Then came the Mental Capacity Act, followed by Deprivation of Liberty Standards' (euphemistically known as 'dols'). People with dementia are presumed to have capacity, unless shown otherwise by individual assessment. No longer was a collective approach to safety permissible.

Another use of common law in mental health practice is to detain or restrain a disturbed patient in a scenario where there is clear danger but the Mental Health Act cannot be readily applied.Nurses have six hours of holding power (Section 5.4) should no psychiatrist be available, but this contingency is rarely applied, partly due to uncertainty about whether the nurse would be acting lawfully. If a person with paranoid psychosis awaiting admission tries to leave, and has exited the ward area, can he be forcefully brought back?The quick-thinking nurse doesn't wait to consult the code of practice, but acts immediately in the interests of the patient and public. This unwritten power still exists, but is frowned upon. Tragedies have occurred when nurses feel hamstrung by legal complexity.

English legal heritage is rich and remains widely respected across the world. The Magna Carta established individual liberties, and it was the foundation for our common law. This is the body of legal principles made by itinerant judges, who travelled around the realm administering equitable justice. It developed through precedent, and by discussion between judges, who were always eminent members of the legal profession. Unlike the administrative hierarchy of European justice, English judges are endowed with autonomy, as described by RM Jackson in The Machinery of Justice in England: -

'The English tradition is that the legal profession is practically an autonomous body, the judges being drawn from its ranks when they are not less than middle-aged. The best practising lawyers are elevated to the judiciary, where the terms of their appointment ensure that they shall be independent of administrative interference. Hence for the common lawyer the revered figure and oracle is the judge.'

Common law was instilled in the American Bill of Rights, and is prominent in the legal system of Canada, Australia, New Zealand and other former colonies of the British Empire. Unlike the codified Napoleonic or Teutonic legislature of Roman derivation, common law has no rule book. It is conservative in being informed by historical judgments rather than by social whims, but nothing is set in stone. By its very nature common law evolves, taking a pragmatic approach in contrast with the axiomatic continental legal culture. Common law is like a river, deepening and widening over the centuries. Sadly, much of its tributaries have been dammed and its delta is drying out.

As explained by Jonathan Gaisman QC in Standpoint, common law has been steadily undermined in its country of origin by the relentless expansion of statute law, which often imposes political ideology. The Equality Act 2010 he describes as 'a particularly lengthy and dismal example of Soviet-style draftsmanship'. Thousands of new crimes have been created since New Labour took office in 1997, including vague offences of 'controlling behaviour' and 'hate crime', with victims receiving payments for 'hurt feelings'. But the main culprits are the European Union and European Court of Human Rights. Since we acquiesced to the Treaty of Rome in 1973, the naturally flowing streams of our common law have been replaced by a network of canals, to the doctrinaire design of Brussels and Strasbourg.

The ECHR regularly overturns the careful verdicts of British justice (Scottish as well as English law), undermining democracy and national interest. It has never respected common law submissions, making majority decisions rather than judging the case on merit alone. The whole concept of human rights has been tarnished by ECHR judgments favouring illegal immigrants over citizens and terrorists over their targets. As Charles Moore noted in the Daily Telegraph, this is a prime example of an elite overriding the sensibilities of ordinary people. We should build on the momentum of Brexit to break free from the ECHR too. Otherwise, Theresa May's promise of a properly sovereign nation making its own laws will be broken. In its ultimate authority, the ECHR won't let us determine immigration policy, and our Supreme Court isn't really supreme. Unhelpfully our judicial establishment has succumbed to the march through the institutions. Several judges are brazenly Europhile, disinclined to relish the opportunities presented by leaving the EU.

The most fruitful avenue for a resurgence of common law is in international commerce. Indeed, English common law prevails in commercial contracts. As we struggle to negotiate the future relationship with the EU, contrast the Juncker-Barnier protectionist bloc with the Anglo-American belief that free trade makes the world wealthier. Trade deals are mistakenly seen by bureaucrats as the only mechanism for exchange of goods and services. With such ingrained attitudinal differences it is not surprising that pooling of sovereignty has failed us. It failed the countries of Commonwealth too, such as the Cypriot potato farmers and Caribbean sugar industry.

Common law is not a licence for people in power to do what they like. Its guiding principle is the least force necessary. The Mental Capacity Act doesn't really improve patients' rights. Capacity assessment for every decision is a ridiculous burden on hard-pressed care staff. Wary of an unannounced visit by the Care Quality Commission inspectorate, nurses spend much time tapping into the computer justifying mundane activities. The CQC is prioritising these assessments, seeing staff shortcomings rather than the law as the ass. Nurses have learned the mantra: if it's not recorded, it didn't happen.

Gaisman asks, in the title of his article, 'will the genius of common law survive?' I hope so, because common law is framed by common sense. There is no better way to express our new-found freedom.