After the defeat of James II in 1690 a series of “penal laws” were passed by the Irish Parliament, dominated by the Protestant minority who had supported William III. The first, in 1695, took away the right of Catholics to bear arms. Another forbade Catholics to go overseas for education and prohibited them from teaching or running schools within Ireland. The most important however was the Act to Prevent the Further Growth of Popery (1704). This prevented Catholics from buying land or inheriting it from Protestants, or from leasing land for more than 31 years.4 At about this time the potato was introduced as a major crop. The combination of the legislation and the new crop was ultimately disastrous.
The penal laws, together with other legislation, created a set of powerful and perverse incentives. Because Catholic tenant farmers could not own land or hold it on anything but short-term leases, with little or no security of tenure, they had no incentive to improve their land or modernize agricultural practice. All the benefit would go to the hated alien class of Protestant landlords in higher rents or more expensive leases.
The potato made it possible to support a family on a very small piece of land, with a labor-intensive crop. This combination of legal institutions and the potato had the following effects. Irish agriculture did not improve or develop, but remained a subsistence, labor-intensive activity. The land was repeatedly subdivided since there was no incentive to improve production and profitability by consolidating farms, and a family could survive on a small area because of the high yield of the nutritious potato.
By 1841, 45 percent of all holdings were of less than five acres. The lack of capital and the restraints on the Catholic majority meant that Irish commerce and manufacturing did not develop, and by 1841, 5.5 million out of a population of over 8 million were totally dependent on agriculture. The final, extra twist was the impact of the Corn Laws, the system of protection for English agriculture set up in the early nineteenth century that prohibited the import of grain until prices reached a particular level. This had the effect of preserving the flawed Irish farming system.
How laws aimed at to restrict the rights of Catholics eventually led to the Irish Potato Famine.