um it depends on the arts faculty if they apporve of ur units of study. If they do then that can contribute towards ur arts degree and then you can complete ur law degree in 5 years. However if they dont get apporve and you dont receive the minimum credit poinrs after 5 years for arts, then you would not finish within 5 years. You might finish a semester later but latest two semesters. How it works for transfer into second year is that second year is mostly law as you should have completed the required amount of study for 2nd year law student in the other degree if u already did that degree.
i.e. if i did arts 1st year and transferred into arts/law, i already did two years worth of content for the combined degree so in 2nd year my focus will be law. whereas a normal arts/law student does half the content of a normal arts student in 1st year and the other half in 2nd year.
from then 3rd,4th and 5th year are the same for everyone.
hope thats clear.