How do you define justified, though? If it was passed by the elected House of Commons, how can an unelected body delaying it be justified? And one person's definition of "justified" is always going to be different from another's.
I wish they'd just abolished it in 1911, but that would have caused an uproar!
By "justified" I meant that the House of Lords nowadays normally uses its veto power only to block legislation that is unconstitutional or violates fundamental civil rights. For example, the House of Lords , if I recall it correctly, recently held up legislation that restricted trial by jury or extended the amount of time a person can be detained without being formally charged with a criminal offence.
Keep in the mind that the UK, unlike for example the US and Canada, does not have a written constitution or a Supreme Court that is capable of striking down unconstitutional legislation. The suspensive veto power of House of Lords therefore fulfills in part the role which the (equally unelected) courts play in other countries.