The charged can be proved by burden and standard of proof
It is necessary to examine in advising Arvin, where the burden of proof lies on each of the elements of the offence with which Arvin is charged. The charged can be proved by burden and standard of proof on two points Actus Reus and Mens Rea as to prove the actions and the intent of the defendant. The general and the basic rule in criminal cases laid down by Viscont Sankey LC  is that it is for the prosecution to prove all the elements of an offence beyond reasonable doubts. Woolmington v Dpp  and until proven guilty Arvin has a presumption of innocence as in Art 6(2) ECHR as burden and high standard of proof is required to prove an assertion that assertion is correct.
To proof the burden that which party has in criminal trial the accused must satisfy the jury of their innocence or must the prosecution convince the jury of their guilt. However the question to be addressed here are whether the statute reverses the legal burden of proof on any aspect of the offence, whether the evidential burden may be placed on the defendant on any aspect or whether the legal burden should remain exclusively with the prosecution.
As in the given statute parliament intention was to control who acts wilfully as without lawful excuse commits an offence and if accused show that they were on their way to return the books and the section then they have a valid defence for everyone including law students on the evidence of proof.
As the common law principle “He who asserts must prove". The question of proving the offence as who acts wilfully without lawful excuse commits an offence is usually on the prosecution, however between defence and prosecution evidential and legal burden can be split as the notion given by Devlin J in Hill v Baxter  as the heavier and the lighter version  . Thayer  described the peculiar duty of him who has the risk of any given proposition on which the parties are at issue who will lose the case if he does not make this proposition out, when all has been said and done.
The general rule is that he who bears the legal burden bears the evidential burden as well  . The analysis of the statute given in this question can be seen in the light of this version  . Roberts  points that evidential burden is not strictly a burden of proof at all but only a burden of adducing evidence (L v Dpp  ), however as a matter of fact it remains for a judge alone. The party with the legal burden of proof also bears an evidential burden on that issue and has duty to adduce sufficient evidence to raise the issue determined by the rules of substantive law  . The burden party loses if there is no evidence at all or if the evidence does not satisfy the finder of fact as persuasive or probative burden as Lord Halbury stated in the case of Wakelin v London SWR  .
As in Hill v Baxter J Devlin said the accused had the evidential burden  to adduce enough evidence to raise the issue of defence but the prosecution bore the legal burden of disproving the defence. Legal burden is on prosecution to prove beyond reasonable doubt every element of the offence with which the defendant is charged during the entire course of trial however evidential burden on the prosecution to tender relevant and admissible evidence on every element of the offence with which the defendant is charged and has duty to adduce sufficient evidence to raise the issue determined by the rules of substantive law  .
In the case of Hunt  Lord Bingham referred to Lord Griffiths statement, if the statute was unclear the court should look to other considerations to determine the intention of parliament such as the mischief at which the act was aimed and practical consideration affecting the burden of proof and in particular the ease or difficulty the respective parties would encounter in discharging the burden. It is possible on the wording of the statute it seems prosecution lays the burden of proof to prove that Arvin had wilfully not returned the books. However Dowrkin  argued that people have a profound right not to be convicted of crimes of which they are innocent.
Lord Bingham in AG Reference  stated an evidential burden is not a burden of proof  . It is a burden of proof rising on the evidence in the case an issue as to the matter in question fit for consideration by the tribunal of fact. If an issue is properly raised it is for the prosecutor to prove beyond reasonable doubt that that ground of exoneration does not avail the defendant. Legal burden governs what he says when directing the jury about how they are to reach there verdict  . However in Dpp v Sheldrake  Clarke LJ stated “it is… sensible to continue to use that is required to discharge the burden as to identify evidence raising the issue". The subsequent cases of Lambert  and Johnston  , Lords considered the test of fairness, proportionality and reasonableness in the light of Art 3(1) of Human Rights Act 1998 and Art 6 of ECHR  .
Lord Nicholls also explained in order to maintain the balance between society and the individual, rigid and inflexible standards should not be imposed on the legislature attempt to resolve the difficult and intransient problems  . In Dpp v Sheldrake  the House of Lords examined the status of burden of proof in a case involving the defence to placed burden on defendant as to proof there was no likelihood of the defendant on the issue in question. The Strasbourg jurisprudence in Salabiaku v France  does not mean that the burden of proof being on the prosecutor was an absolute. It was an important to have a reasonable balance between the public and individual interest.
As here Arvin can show that his believing of the books not overdue and he didn’t act wilfully as he forgot and under defence of subsection by being on his way he been arrested and the defence in subsection (4) as not a popular books can discharge him from being liable as prosecution legal burden to proof can be discharge on famous cases and the defences based on statutory exception.
The issue of reverse burden of proof by considering the reverse burden and onus of proof in relation to Art 6(2) ECHR the presumption of innocence  leads to the proposition that the burden of accused guilt rests on the prosecution all the times and any doubts should benefit the accused  . In R v lambert, R v Ali, R v Jordon  decided in the context of reverse burden of proof prove in a statute could be interpreted as imposing on evidential burden Lord Steyn stated that legislative interference with the presumption of innocence requires justification and must not be freer than necessary, however the principle of proportionality must be observed  .
In Summing up the Standard of proof remains on showing the proof beyond reasonable doubts or proof on the balance of probabilities to the judge and the jury. The standard of proof imposed on the prosecution in order to discharge the legal burden f proof beyond reasonable doubts and adopted for the policy reasons to be fair and not to wrongfully convict innocent person. However this proof remains a high degree of probability as lord Denning stated in case of Miller v Minister of Pensions  .
None the less it remained the problematic as what constitute beyond reasonable doubt as pretty certain  or satisfied  or reasonably sure  or reasonably satisfied so can u fell sure by Lord Goddard  however in case of Stephens  Court of Appeal drawn the distinction on the previous cases and established that the jury should be told that they have to satisfied so that they are sure of guilt. Where as in the case of Carr-Briant Lord Humphreys  stated that the legal burden is on the accused that burden is discharged on the proof of probabilities where unless the contrary is proved the jury should be directed that it is for them to decide that the burden of proof required is less than required at the hands of prosecution in proving the case beyond reasonable doubt, which may be discharged by evidence satisfying jury of the probability. By the given statute the defendant was asked being to prove something within his knowledge. Placing the burden on him was a proportionate response which maintained the balance between the public interest and the individual rights.
There is no likelihood Arvin would argue on insanity defence as the Roberts and Zuckerman  points that the insanity exception is of limited practical significance as of not guilty be reason of insanity meant mandatory detention in hospital.
As Mundy argues  one ought to not to run away the idea of Lambert that parliament can legitimately cast a legal burden of proof on a defendant. In the case of Lambert stated on the presumption of innocence, the legislation has a choice. First to impose a legal burden of proof on the accused unless satisfies on the balance of probabilities, secondly to impose the evidential burden only on accused. As the phrase given in case “a defence for the accused to prove" and held that if the prosecution produced evidence of defendant’s guilt the defence has to adduce some evidence of not aware of the nature of the substance. In L v DPP  the court considered S 139(4) of Criminal Justice Act 1988 and placed the legal burden on the accused to prove that he had a good reason or lawful authority as a defence to a charge under S. 139(1  ).
The issue of statutory implied exception can be established at issue as the effect of s101 Magistrate’s Court Act 1980  provides, where defendant relies for his defence on any exception, provision, exemption, excuse or qualification he bears the burden on the proving of exception. The House of Lords held that this enacted a principle of common law that the statute could implicitly shift the burden of proof from prosecution to defence.
If proved the legal burden of the proof was on the prosecution to persuade the jury beyond reasonable doubts that the accused did have the knowledge of the nature of substance. As the case of Johnston  if accused show that he believed on reasonable grounds the use of sign than he has a valid defence in the given Act.