First in time is a descriptive priority rule indicating that, where competing legal rights conflict, the right created earlier will usually prevail over one created later. It is not generally defined in UK or Irish legislation, but is widely used in practice across property law, secured transactions, insolvency, intellectual property and civil procedure.In England and Wales and Northern Ireland, it commonly underpins priority between equitable interests (for example, between competing equitable mortgages) and between unregistered interests in land, subject to statutory regimes such as the Land Registration Acts and the rules on bona fide purchasers for value without notice.In Scotland, similar concepts operate through the law of priorities in real rights, where earlier effective constitution (often by registration) normally defeats later rights, subject to statutory modification.In Ireland, “first in time” informs priority disputes in land law, security interests and judgment enforcement, again overlaid by registration systems and statutory exceptions.Across all four jurisdictions, the principle is frequently displaced or modified by legislation, registration requirements, notice, estoppel, contractual subordination, or specific statutory priority rules, so it operates as a starting point rather than an absolute rule.